I have a USA-made SAE and Metric folding set at home that's held up well over the years. I'll see if I can find the name/model.
I've got an old set of Craftsman allen wrenches. If you go this route, make sure the product indicates Full Life Time Warranty, as they have some hand tools w/o the lifetime warranty.
I'm a fan of Bondhus. I'm a machinist and use them daily at work. The set I have now have lasted me 5+ years.
I own about 1/2 dozen sets of the Pine Ridge Archery Archer's Allen Wrenches. A great tool at an affordable price. http://shop.pineridgearchery.com/pr.../part_number=2520/101.1.1.1.733.0.0.0.0?pp=12&
This is the wrench I have: http://www.amazon.com/Eklind-20911-Fold-Up-64-Inch-4-Inch/dp/B000189QNS Its solid.
I use Bondhus at work. They seem to hold up really well. I actually have a Mac set in my archery box right now. If you look at the side of each wrench they are stamped "Bondhus". set from my electronic carrier pigeon
I bought a DeWalt set, its a little bulky, but they have the ability to lock in any position you want and the other dont flop out while your trying to use it. Plus a life time warranty. so far so good.
heres the link http://www.homedepot.com/h_d1/N-5yc1v/R-202710518/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=allen+wrenches&storeId=10051