We actually made gloves for our Roy. I agree with the quality of the online gloves, and I also wanted a cloth with a bit of shimmer/metallic element, something that looked like it should be able to make a spark when snapped. With this in mind, I stopped by Jo-Ann's and got a small amount (1/8 or 1/4 yd, can't remember which) 4-way stretch swimsuit fabric in white. Any 4-way stretch fabric will work for this method, though.
To make a nice but super easy Roy glove, just get your fabric, your Roy's hand (preferably still attached to your Roy), and a pen or pencil, something with a pointy tip (chalk won't work). Fold your fabric so that you have a square of fabric a bit bigger than the hand, right sides together. To made the next parts easier, just cut the square off the rest of the fabric now. Have your Roy put their hand on the fabric, hand-turkey style (in case you don't do hand turkeys, that's with fingers splayed, but not the entire way). Trace around the hand, and a few inches up the wrist. Remove hand, sew along that line. It's fun but absolutely unnecessary to try the glove on now (you'll have a square webbed hand!). cut the extra fabric off very close to the stitch line. Fray check if the fabric seems to want to fray. Try the glove on now, and figure out where along the wrist to cut it. Cut that edge with a bit extra to turn under, and hem it. Now turn the glove right side out and draw the symbol on with a fabric paint marker (I found them at Jo-Anns). Make sure the glove is on when you do this! Voila! Super easy glove (and I was scared it would take forever, it took maybe 10 minutes start to finish (an artist friend did the circle, I'm not nearly so good at drawing)).
This is the only pic we've really got online yet.