I'd pass myself but for range mags I guess they'll do. I have some Thermolds for about the same price for that task but should have kicked in a few bucks more for something better.
For serious business I'd go with USGI or PMAGs.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together. You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek