I'm one of the seamstresses that Scarlet mentioned. I would offer my services, but I'm getting ready to make a big move and will be shutting down commissions for a few months. I hope you can find someone to make the dress for you in time.
As far as pricing, the price should reflect the quality and detail. I've seen some costumes priced around $200 (or even much less) that aren't worth near that much, but others selling the same character's costume for $1000 and it would be worth every penny (if you had that sort of money laying around, that is!) Sometimes you can work with a seamstress, tell them your budget, and they can work the amount of detail around that. I have done quite a bit of that in the past-- Sometimes it's the difference between using fabric paint or embroidering details, or a detailed beadwork pattern could be simplified, etc. For Tiana, the middle layer of the skirt could be ommitted (there are 3 of them!) or a premade flower applique/broach could be used instead of a hand-made water-lily.
Of course, then the amount the seamstress charges per estimated hour of work will vary. I price commissions by estimating the amount of fabric needed (or if I've made that costume before, just looking back at how much it actually took), then breaking down the parts of the costume and figuring out how much time it will make. Then that time is multiplied by the hourly amount and added to the estimated cost of the fabric. How much a seamstress charges per hour will vary based on many variables like how much demand there is for their services and where they see their quality level. I am able to charge less right now because I only officially went into business last year. Until I build up a decent portfolio of commissioned costumes, rather than just my own, I don't plan to charge much. Once I have a better portfolio and more business (especially if I have more requests than time), my price will go up. If you want to take a peek, my business page is here: http://www.facebook.com/pages/Nessab...38363899532291
Feel free to "like" it. I'd love to work with you in the future if my schedule allows.
Now, as for Pocahantas advice, fabric-wise, a fake suede like this http://www.joann.com/joann/catalog/p...DID=xprd728336
is a great choice. It doesn't fray, so you can get away with not finishing the edges, and would work well for the fringed trim on the dress. It also comes in the right colour-pallet for Pocahantas, and is quite affordable. I rarely use patterns (I drape directly on my dressform), so I'm not much help in picking patterns. Does the friend who owns the machine sew? If so, pick her brain on how to get started. See if she can teach you the basics. Or you could try to take a basic sewing class at Joann or another local fabric store. Often, the class instructors get excited about helping you figure out a project.