I seen some of these on Gunbroker and was wondering if they are quality or not...

magfaq.tripod.com/

Cheaper than Dirt had some, and they were quite filthy, and well worn.  It was necessary to disassemble and SCRUB with a bottle brush and hot soapy water.  After this, they seemed smooth, though a few had cracked feelips.

Like Troy, I would use these ONLY for range use.

But before buying these, I would advise spending your money on USGI mags, any manufacturer except Cooper.

Even Coopers may be alright IF:

(1) the welds look OK.  Chisel down the price, and use them for the mag body and floorplate only.  Put in a new spring and green follower, and it will function OK.  

(2) All Coopers I have seen had weak springs, and would not feed the last 5 or 6 rounds.  The spring was so weak the follower could not actuate the bolt stop.

Try to buy on sight or roll dice on bulk. Some have cracked feed lips from age/heat. Good beater range mags overall for $10, much better off with used USGI for $15-20 IMO. And I like my $20 new Thermolds, so I am not anti plastic mag. Orlites are just often tired.