+1 for Bravo Company USA. Purchased many times from them.

Their brand of mags is one of the better makes out there. Beware some companies, such as Thermold, Promag, etc... I also am highly suspicious of some Phillipine mags that have been selling for $8-9. For USGI, D&H brand sold by BCM is how I'll go.

+1 for Pmags! They also are excellent, although I don't worry about getting the ones with the window for round count. Its too low to do much good.
Pmags are NOT indestructable however. Anything can break, and Pmags also have broken. Any magazine can fail, but the Pmags have a good reputation for their quality and their customer service. I myself have around 20 of them.