I bought a no-name one off eBay and its great. Small, solid built, USB2, Firewire, UDMA 133 and an extra cable so that if you are using a non-powered Firewire port (like a mini-firewire on a laptop) you can plug this cable into the PS/2 port and plug the other end into the enclosure to power it. The PS/2 power is even a passthrough so it doesn't take the port up.
But this was a 2.5" enclosure, not a 3.5 (3.5's will always be self powered rather than host powered).
But I doubt there are any really crap enclosures out there, just check out the features before hand.
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RetroTracks - Classic Computer and Game Music