Hey, Drtooth. YES you can buy Build A Bear "buildable" products pre-stuffed. They offer a small handful in the stores that are already made/dressed, and when you order them Online they come already made. I DO think you can order them as-is and take them to a store and "build" them for free, but that's beside the point.
I'm not sure if there is a price difference, but if there is it's not enough to talk about.
That's the other thing with Build A Bear products, if you EVER have any trouble with one, regardless of how old or whos fault it is, they will take care of it. I bought Shrek a few years ago before the second movie came out, and a seam in his face popped. I took him back, and they said they'd stitch him back up, no reciept, no charge, no worries. That's why i'm so excited about this, they really do a great job.
...and I guess you could dress scooter in corsets too...