Well, if all you want is a classic mag, you can find them over at AO for about $150 or so. However, what I would suggest is that you spend the extra cash and get an ULE mag with a level 10. You can get them used from about $250 on up. New, the RogueFactor Paradigm version of the ULE RT PRO is a great marker. They run anywhere from $350-$500.
The best place to find deals on automags is
www.automags.org in thier b/s/t. Also there are a few on ebay.
Mags are great markers btw.. you can't kill them. Once you learn to care for it (about 15 minutes) you will have a great marker that will never let you down.
Good luck!