I am a carpenter by trade, but I also do alot of wrenching on the side. A buddy of mine has alot of northern tools, he likes them and hasn't had many break that I know of. I just suggested Craftsman since they are more plentiful than Northern stores. 20mm is just a hair bigger than 3/4".WOW!!!! where do you live?? :laughing: I will check out sears. I mentioned northern tool because they offer a Jumbo wrench set, I do not know what 20mm equates to.
As for getting a good torque wrench, look on Ebay. I have bought a few of mine off there, all are Snap-On and I never paid over $85 for any of them. I paid $85 including shipping for my 1/2" Snappy clicker with 200lbft capacity.