The Harbor Freight torque wrenches often go for $10 each, so that's about an hour's worth of labor for each torque wrench. Mainly, you'll want the 1/2" and 3/8" drive... you probably won't use the 1/4" as much so I would get that last.
Some people have doubts about HFT,quality but their torque wrenches are actually pretty decent. They are suppose to be +/- 4% accurate, but the ones I've gotten have all been within +/- 2% accuracy at all 3 points (low, mid, high). They are all metal construction too so no chance of plastic bits breaking like the craftsman and some other brands. Wait for the sale and keep an eye out for the coupons at HFT and put down your $10 bucks and get one! Really incredible value at $10...
I recently took a close look at the new Kobalt torque wrenches at Lowe's. They aren't that cheap ($80), but more affordable than some high end brands. They were all metal construction as well and the calibration certificate stated the one I was looking at was +/- 1% accurate at 3 points!! You don't usually expect that accuracy with these click-types, but that was pretty good.
By the way, I don't know of ANY torque wrench that really has a "lifetime warranty". Some people will tell you that Husky, Kobalt, or Craftsman has a lifetime warranty, but if you read the fine print or on the back of the user's manual, you'll find that it's usually 1yr warranty and 90 day on calibration.