I have 2 dual docks, one Thermaltake Black X and one Startech. I've had zero problems with the Black X, but the only design flaw is that you can only turn both drives on at once. Well, you could insert the drive while the switch is on, but that's a little ghetto. The Startech died on me because it kept powering on and off when I had 2 drives in. It screwed up one of my hard drives because it kept powering off and on constantly causing mft data loss. I couldn't recover any of the data. I wasn't so angry because it was just shows I recorded from Discovery Channel...can always catch reruns of those. If it were some of the stuff I worked on or downloaded I would be pissed! BTW, I got it replaced by Tiger, and the new unit has been working for a good 8 months with only the only problem being the LED on one of the slots not turning on.
Keep checking Tiger, Newegg, and Buy.com for hard drive deals. Sometimes you get instant rebates, and you may be able to get $20 or $30 off the drive you're looking for. Check daily or at least weekly.
For hard drives, I've used the Hitachi Deskstar 2TB, Seagate Barracuda 1TB, and Western Digital Caviar Green 2TB. They are all great, but since you mentioned 2TB, I'll talk about those and my experience with them. The Hitachi is a steal for a 7200RPM drive. It's fast and reliable, but it does make some noise and gets hot. The price of the WD lower then the Hitachi, but it has some drawbacks. Definitely not for use in RAID 1 or any mirroring. I wouldn't use the WD as the OS's working hard drive, but as an external it's great. Also it's quiet as can be and stays nice and cool. Make sure you get the WD20EARS not the WD20EADS if you go WD. I think the other version is crap by some of the reviews I've read.