I faced this same consideration when I went off to college a couple years ago,couldn't really afford to play paintball anymore with tuititon fees until recently so I got involved with airsoft. on the matter of Gas vs. Electic operation, i personally prefer electirc for a few reasons. One of the biggest being if you don't play at an official field that doesn't have a pro shop finding green gas or substitues for it can be troublesome. A lot of companies stopped shipping the cans because of new regulations (that was a year or two ago, but i've since seena couple online retailers start doing it again) Also, gas doesn't always work well in the winter if your into winter games, sometimes it doesn't work at all, it all depends on the temperature. Also, gas mags don't usually hold a lot of BBs (30-50is), and if you're not running a direct line from a tank (those guns are wicked expensive sometimes) you can get 2 -3 mags worth of BBs per fill. Thats why I prefer electirc, but its a matter of prefference and what seasons you play in.
I have a JG M4s and i haven't had a need to get anything else. it works great, gets around 1,500-2,000 shots on a 9.6v 1600mha battery, and if you get mid cap mags (hold 100-150) you can be a beast at support, just hold down the trigger!
For a starter gun for electic i would get something by JG. They don't have a lot of the bells and whistles but it seems like you're not really after that and honestly you don't really need it for this sport most of the time. For a gas rifle, G&G makes some pretty good stuff that won't break bank, but you're going to need a lot of mags and they aren't cheap ($30-40 for a 30 round mag)
Its an entierly different sport, i though about just sticking with gas at first too, but honestly Electric is cheaper to maintain and in my opinion works a lot better for support, but its all a matter of preference.