Only really need precision for things like aluminum threads or engine internals (which won't have high enough torque to require 1/2"). A $16 torque wrench is fine for 99% of the large crude things you need a 1/2" wrench for (eg: lug and axle nut type stuff). Get one that is 20% or so higher capacity than your max torque value you need. The difference in cost is how long it stays calibrated. If you're not using it every day, it should last a while.
Tested my harbor freight cheapo 1/2" against a certified calibrated SnapOn beam wrench at 100 lb-ft and it was spot on. I only really needed it for lug nuts, everything else is small enough for 3/8" and my rear axle nuts are 250 ft lbs so those just get an impact (only seen beam wrenches go that high in 1/2" and good luck with that!)
If you still want a good one, expect to spend $200-300.