I recently went through the whole process of trying to decide on a few good torque wrenches. I bought one that looked exactly like the harbor freight ones and tested it against a known good wrenche that a friend of mine who is a mechanic has. The one that I bought would torque to something like 48lbs when set at 30, so it was waaaay off. I exchanged it for another and it wasn't as bad, but was still off quite a bit, so I got my money back.
I ended up reading a lot about torque wrenches and ended up picking up two CDI torque wrenches off of Ebay for around $110 a piece. I bought one that was 30-200 in lb and one 10-100 lb ft. They both came with calibration sheets and the farthest that either of the were off was like 2%. The company is owned by Snap On and makes most of Snap Ons torque wrenches. I found out that the only difference between the CDI and Snap On wrenches are the ratchet heads and the name on the handle. Btw, I'm talking about the micrometer torque wrenches.
The split beam wrenches like the Precision Instruments one that was poster earlier, are also supposed to be very good and don't ever need to be calibrated like the micrometer wrenches. I would have gotten one, but it they just weren't quite what I wanted.
If you want to keep the costs down I'd probably go with the Husky brand from Home Depot. They are supposed to be pretty good and offer an actual lifetime warranty. I'd avoid the Craftsman brand after reading a ton of reviews on them breaking after very little use.