$1000 minimum IMO, 1K will load you up nicely between gear and a decent AK. Do not rush into any purchases, take your time and do your research. Talk to a airsoft gunsmith as well when you narrow down your choice between two models, pick his brain as far as durability, upgradability, replacement parts availability. I admit I rushed head first into it and made a few mistakes, luckly not costly mistakes
1 - Battery (in decent shape or 2 if there iffy)
Good charger (do not trust those chargers that come with, they suck huge)
camel back (depends on area your in and style of play, I carry 2-3 litres on me always)
Good to get after;
Chest rig (ciras, denalli....... personal preference)
camo for area
shegmah / boonie cap .... (again personal preference).
Just my 2cents.