The TXS0206 looks great - designed for this, and it's cheap. Unfortunately, the available packaging (BGA) really makes it a non-starter for a lot of hobby stuff.
I'd like to know what Sparkfun's using for their microSD breakout:
https://www.sparkfun.com/products/13041
I'm not sure whether the chip shown is a tiny pinned one or a DFN with the contacts exposed on the sides, but at least I might stand a chance of soldering that.