if you are playing at normal sites on normal days make sure they'll let you use you're own stuff, most sites that will won't like it if you turn up and starts shooting 25 bps, also it'll cost you a fortune in paint (they won't let you use your own on a normal day).
If you are playing walk-ons start off with something second-hand like an A5 (advantage is it has a built in hopper) if you like the milsim route or a £100 - £200 secondhand electro off here if that's more your style is probably a good way to start, something like the H18 you'll be changing after a couple of walkon's if you enjoy it and if you don't enjoy then you've wasted your money. If you buy a secondhand £150 electro you'd be able to get most of your cash back if you didn't like it by selling it on.
If you are playing walk-ons start off with something second-hand like an A5 (advantage is it has a built in hopper) if you like the milsim route or a £100 - £200 secondhand electro off here if that's more your style is probably a good way to start, something like the H18 you'll be changing after a couple of walkon's if you enjoy it and if you don't enjoy then you've wasted your money. If you buy a secondhand £150 electro you'd be able to get most of your cash back if you didn't like it by selling it on.