As stated above, AEG is your best bet for a first timer. There are many more variables to consider when buying a gas gun (temperature on game days even comes into play), and gas guns with their accessories and consumables are much more expensive to game and maintain. They're also a pain in the ass to repair if something goes internally. Get a G&P M4 or something similar, decent quality and will last you a while without burning holes in your pockets. Toronto Airsoft has a multitude of good AEG's listed for purchase (just an example). Also, WE Tech has an M4 AEG on the market now that is priced very low, but fires like a champ (I own one myself and love it). Just gotta search around and compare, compare, compare.
Guardians of Asgaard
"The judge meeting is arranged for terrorist." - G&P Laser Product
Primary - Z-Custom VFC ZTW
LifeLine - TM Glock G18C