Welcome Fafor,
To be honest, your probably better off buying in the cheaper ranges, but that doesn't mean it'll be rubbish, far from it in fact, brands like cyma & JG have great reputations, big ranges to choose from, & luckily for you some excellent retailers virtually on your doorstep.
With your budget why not buy 2, everyone needs a back up, & don't be thinking about upgrades yet, most brands are more than adequate straight out of the box, if fps/range/accuracy is fair to good, then what more do you need, maybe then only think about upgrades if something breaks.
Next choice is what models to choose, I always that think 2 with magazine compatibility should be considered, makes life much easier if you find yourself dashing back to the safezone mid game to swap guns, but if AK's are your thing you might feel a little bit limited, to me they all look alike lol, so maybe consider a long model & a short model, gives better options for cqb sites etc.
Alternatively consider an armalite model, m4 derivative of which there are hundreds (or so it would seem), but being stanag mags you could get another m4 model, or maybe consider a bullpup such as an L85, a tavor, an fn2000/fn2010, an fnc, a G36 with a maxwell conversion, probably even more that I've forgotten about, the choices are endless.
Good luck with what you choose.