The M4 is sound, look at this beauty...
Really is not that expensive for its specs, 300fps! This place here has a decent variety of Airsoft Guns
. It came with a battery and charger so it's pretty handy as a first gun, eases you in nicely while you save up for a better one after a bit of playing around!
I'm a bit of a newbie myself but I hope that helps you out a bit!