Usually $20 for a gun/battery/some mags...maybe BBs, but you should have another $10 to buy a bag of BBs (they'll last a while).
Post up in the game thread that you're a newbie and need a rental. Someone will reply/PM one way or another.
IMHO...you're a ways off from worrying about upgrades. There'll be plenty of time to do all that once you've picked out what you want to run with. Nothing is more of a waste of money than buying an AEG, dumping $200-300+ of parts into it...and then finding out that you'd rather have a different type of AEG altogether.
So far as buying from overseas or buying locally...lots of guys go either way. For me...I buy local. I like to chit chat with the owner of the shop...hear what's coming down the pipe next...physically see&touch this and that. I also prefer to see something, pay for it, and walk out with it in my hands. I really don't like ordering off a website, hoping that it's being packed/shipped ok, hoping that customs processes it quickly, hoping that the postal system doesn't lose/break/damage something. I don't like missing deliveries and then having to run over to the post office to pick up parcels.
So...I buy local. With a cash deal on the table it's about the same as if I ordered it from overseas, shipped and got dinged with duties. Sometimes better...sometimes just a bit more.
I deal with Jugglez at Airsoftparts.ca. I cannot recommend him enough to anyone looking for quality parts/accessories with fast shipping.