E-mag... They're a bit hard to come by nowadays.
www.Tunamart.com will give you the best price... Talk to him about a custom one... Bsaicly you have a few things to screw with...
Since tunaman sells RPG parts, you could ask him to build you something using parts from
www.TheMagSmith.com. For example: Exile Body, Splinter Rail, Gripper Snatchgrip, etc.
Of course, you cant choose a foregrip or trigger frame if you want to go the emag route. I reccomend the e-mag for a tourney player.. You'll be much happier becuase you can switch from mechanical to electronic mode with the flick of a switch.
Or if you want a mech, get an RPG Paradigm custom marker.