[mcguyver]

The WE guns are very cheap in Asia, like about $100 or less. The finish on the cast parts is crappy, out of spec tolerances and flash that has been known to cause everything from rough slide movement to poor mating of the mag valve/cylinder inlet.

The CO2 mag in a stock Marui gun will likely be too much pressure and cause you to be buying a new Marui. Definately not recommended. Also, the cool-down on CO2 is pretty extreme, sometimes I couldn't empty half the mag on a single 12g during spring/fall use. Same for the standard mags though too.

Buy a WE if you are willing to have more than one of them. Sometimes 1 gun doesn't work at all, it'll just dump gas back onto your hand and fail to lock the slide on empty mag. But, changing slide/frame combos between guns usually fixes that. It's that poor tolerance issue that usually is not user repairable, especially for new guys.