I have to agree with the many that recommend against a bolt action rifle as your first gun especially with your budget. To get a good bolt action thats worth upgrading will consume most of your budget. Then you'll need to pour at least another $600 into it to give you a "short" range advantage over the AEG toting high-cap tickling mobs that you'll be up against. A range advantage that can be nullified by even the fattest oldest guy out there very quickly. Quite frankly I can't for the life of me figure out why anyone would voluntarily chose to use a BA rifle as their primary in airsoft
. "Sniping" in airsoft isn't what you think it's going to be. Get an AEG which out of the box will have similar or better range. You can still play a sniper type role but won't be handicapped.
My advice to you would be to make a DMR setup. Buy an M16A3, get a TB barrel, a good hop rubber slap a scope and bi-pod on it and you're good to go. I understand King Arms makes the best bang for your buck AR out there. A bit pricier KWA makes a nice one too. Just stay away from G&P.. over priced and over rated IMO, but they sure do look pretty.
Edit** We can't tell you where to buy airsoft because you're under 18, it's against forum rules.