x2, these arent considered very popular so from what Ive seen around here there are still plenty of US made sets at sears. I believe for around $20-30. Other than that it wont be easy to find decent ones for the money unless you look for old used ones. If you didnt mean open ended than you will have a hard time finding double box wrenches for that kind of money too.
I've got Craftsman tappet wrenches and they've been fine when I need them. They have a fairly long reach and a thin head. The price is definitely within your $50 budget.