I had a 2.5″ SATA drive just sitting around unused, which I pulled out of a failed ASUS netbook a while back. The drive was in good condition so I decided to order a USB enclosure to stick it in and make it more useful.
This initiated my usual process of visiting Amazon, viewing products, and reading several reviews. Ultimately, I settled on a Mediasonic ProBox 2.5″ SATA HDD Hard Drive Enclosure – USB 3.0 (H21-SU3). I wasn’t looking to spend very much and it seemed like a good buy at about $15. In addition, it also supports USB 3.0 and my 13″ MacBook Pro has USB 3.0 ports.
I’ve only used it a couple of times but it seems sturdy and I haven’t had any problems with it. I can’t make any claims about how good the USB 3.0 support is since I haven’t really done very much with it. The case is plastic but it feels sturdy and with only one screw it’s very easy to open and close.
Updated 05/22/2013: I bought two more of these after upgrading my MacBook Pro hard drive and my wife’s for use with the old drives.
Updated 07/18/2013: All of these cases are still working great.