Here is my two cents,
I have the KWA MP7 (gas blowback) and love it. I use it for CQB and I plan on making it my primary after seeing people use it effectively in large outdoor milsims by adding the Angry Gun suppressor. However the mags cost around $45-$65.
I have not used the MAC11 (gas blowback) but from what I have been told it is a spray and pray gun... sights are not important as it's not really meant for aiming and shooting.
My recommendation if you want an electric gun (and as has already been mentioned) get an MP5, CYMA makes good durable mid-range MP5s for around $200-$260, and the mags are cheap.
Also consider visiting stores, if you are able to, and get a feel for the guns before you buy any.
A Canadian is someone who knows how to make love in a canoe - Pierre Berton