I think the Rubik's brand 2x2 id your best bet.
Hmmm. Thanks. I saw it in nowstore but as it didn't have edge length I didn't pursue it. I wonder if it can be disassembled, since the latest promo on the rubiks.com site says "Due to the new smoother movement, the 2x2 cube cannot be taken apart and hence we cannot replace any cubes that are broken as a result of attempted dis-assembly".
I'd use the 45mm if i had to, but it's definitely at the top end of the range I want.