I'd say give the cheaper ones a try unless you've heard some reliable sources that have horror stories of them frying shit.
Heck I got the Nyko USB Hub for $14.99.
BEST ADDON INVESTMENT FOR MY PS3 EVAR as it adds 3 more usb ports and a card reader. :3
However this is for the older 80/40/60gb models. Not sure if u can put it on the slim and it would respond normally.
Edit* for those that get it, make sure u have the correct plastic piece in place and once you've slotted it in the left usb port, really push the module up so that you'll hear a "snap"; it means it's secure and not lurching downward where it could get pulled out much too easily.