1. Get out to some local games and check out the differences between a gas rifle and AEG in person. It will make or break your decision.
2. While there...handle a couple of different rifles...does one type fit you better than others
3. While there...get age verified. Guys on this site won't nag you as much and you'll have access to the classifieds/retailers/etc... There are often some smoking hot deals in there.
4. While there...check out what else you'll need to play. Gear/goggles, batteries/chargers for AEGs, propane/adaptors/etc for gas guns. How many mags will be enough for typical play...how many more are desireable. Lights/optics/etc... Comms/gloves/slings/etc...
5. Revisit your budget...make sure you can afford the essentials before you sink it all into the rifle itself.
6. Scratch head a bit figuring out where to get a bit more money...'cause you got to eat and pay the actual game fee
7. By now you're AV has probably kicked in...shop around a bit.
8. Go for it.