Lady Hoshi: I had the same problem. I hate gathering, so what I decided to do was use box pleats instead. I've used them a lot in the past to replace ruffles since most anime-style ruffles look like pleats anyways.
What i usually do is first get a basic skirt pattern for yourself. It would be the width of your hips plus a seam allowance. You would want to decide now if you are going to use side seams or one seam in the back. I've done both ways, and back seams are usually less work. I usually go with that unless your overskirt/dress is going to have side seams and you want to be consistent. You will need to measure the length from your waist to your knees in four places: front middle, sides, and back middle. You will need to draw these points on your pattern and then connect them evenly. Usually the front will just be straight and the back will start where the front left off and curve downwards slightly to allow for your butt.
You will also want to figure out how many layers you want the petticoat to have. You need to multiply the amount of fabric the regular skirt pattern took by three for each layer, and then multiply that by the number of layers you want. For the poofiest petticoat I have made so far, I used seven layers. You might want to use five or six, but seven might also work for you, since you said you want it to be very poofy.
Multiply the length (hips plus a little extra for seam) by 3 and cut out a piece this length. If you're doing side seams there will be two pieces. This tutorial will only be for a back seam because it's easier to write, but you would just have more pieces and seams if you did side seams. After you cut the piece out, do a quick straight stitch along the cut line to keep the piece together. Then pleat it. You will need to pleat the top and the bottom to keep it together.
Line up the flat edge of the pattern to the fold in the bottom of the pleated fabric piece so that the bottom of the petticoat won't need seaming to look finished in the end. Trace the non-straight side onto the pleated piece of fabric as best you can. Remove the pattern and unpleat the large skirt. Connect the dotted lines you made and cut. Do a running stitch along the cut edges to keep the piece together.
If you are using four or less layers, just use this piece as your new pattern and cut out three other pieces and do a running stitch on the cut edges of each piece. Then skip the next two paragraphs and go on to the one after.
If you are going to do more than four layers, it is a good idea to make them sewn to a regular skirt spaced out. I haven't tried this yet, but I plan to on the next petticoat I make. I thought it wouldn't be a problem on my 7-layer petticoat, but it was very difficult to get it through the sewing machine. I probably needed to handsew the last part of the waist band but I never have yet since I'm very lazy when it comes to handsewing. You're going to still cut out another 2 or 3 pieces using the first piece as a pattern (depending on how many layers you want), but after that you will need to position the piece about halfway off the new fabric. As long as you keep the folds parallel, and are taking off an equal amount of fabric on each side, it should be fine. Once you have all six or seven layers cut, sew a straight stitch along the cut edges.
You will also need to make a normal skirt to sew the layers onto. If you used the same fabric for your initial pattern, you can just use that, but if not just use the pattern like you were using the larger piece with the straight side on the fabric fold
Trim very close to the stitches you made, making sure to not cut the stitches. Turn your stitch length to zero and the width to a couple notches below the largest it can go. With your needle centered, line the stitches you made before up to the notch in the center of your presser foot. Don't start at the very edge of the fabric. Start a few inches down and when you finish, go back and get the rest. It helps the machine to not eat your fabric this way. XD The key is to keep a consistent pressure on the fabric using both hands, one in front and one in back, to keep the fabric taut. If it's not going through the machine at a constant rate, you will either get lumps or holes in the stitching. I call this overlocking, but it's basically just embroidering the edges so the fabric doesn't fray. Once you've done it one time, go back over it using the largest width of zig-zag stitch your machine has, or one below the largest.
Sew the ends of each fabric piece together to make tubes. Use a slightly larger seam allowance than you did at the top of the layers (about half inch is good). Then, without trimming, overlock the edge of the fabric. You can do this by picking a random place that isn't too close to the stitch line, doing a mid-width zig-zag stitch first, and then trimming the fabric very close to it. Go back over the smaller zig-zag with the larger one at the same place, and that should completely cover the raw edge.
Then all you have to do is put the box pleats into the top and do a quick stitch to keep 'em in place. And sew all the layers together. This is really easy for the 4-or-less petticoat, but a little more difficult for the one with more layers. If you're doing a larger one, take the full-length pieces and sew them all together with the non-pleated skirt on the bottom. Then take the shorter pieces and stitch them together. Look at them on the skirt and mark about every hand-length where they need to be sewn to fall the same length as the rest of the layers. Then, take the side with the seams showing upside-down and position the overlocked edge about 1/4 from the pins all the way around.
All you need to do now is make a waistband, attach it, and add elastic. You can make a waistband by cutting a piece of material about 3 inches wide by the length of the top of the petticoat you have so far plus about an inch for the seam. Fold over one of the long edges about 1/4" from the edge and do a single seam. Stitch the short edges together using a 1/2" seam and then overlock the edge using the same technique you did on the vertical seam of the petticoat layers.
Take the long side you didn't do a seam on, and stitch it to all the layer of the petticoat on the inner side (the one with the seams and that will be touching your waist). Pull the piece over to the front and edge-stitch the side that you single-seamed. Leave a few inches at the end unseamed. Take a piece of 1" wide elastic and use a safety pin or elastic threaded to pull it through the waist band. Try the skirt on to make sure the elastic allows you to pull the petticoat over your hips and is still tight enough on your waist. Sew the elastic together and trim it. Release it into the waist band and finish sewing the seam you left undone.
If you're looking to find cheap fabric to make a petticoat with, I have found that the dollar bin at wal*mart works well if you don't need a specific color. They usually have pastel green, blue, and pink there in droves. You can always bleach it if you want, white, I think. Otherwise, plain cotton works fine. Sorry this was so long and picture-less. I haven't had time to work on the next petticoat I'm making yet since I've gotten hung up on school and the applique on another project. I will try to get a picture tutorial done as soon as I can. Here are two pictures of what the finished product might look like. They were made using organza, which is a lot more expensive and stiffer than cotton, but this is just to get an idea of the amount of poofiness. You can always starch your cotton if you want it to be more poofy.
My seven layer petticoat: http://images.cosplay.com/showphoto.php?photo=534702
Four layer petticoat I made for Joanie: http://images.cosplay.com/showphoto.php?photo=576282