I went ahead and bought a Great Shape Barbie's blue leotard on eBay.
All I have to do now is buy a toy story-branded Barbie and replace the new clothes with the old ones to make her look more screen-accurate.
I think I'll buy the Ken and Barbie 2 pack because you can't buy Ken on his own and the Animal Lovin' Ken he was based on is super-rare because Pixar went and bought most of them while the movie was in development.
Anywhoo, there's a toy fair on in a week or two in NYC and they'll be announcing the new Toy Story Collection toys, so yay!