Put a dollar a day in a savings account.
On the day you turn 18 you should have more than $1000.00 in the bank.
Then you can look at what is available and will suit your plan.
Working off the current price of an AEG is pointless.
If in the next three years you loose interest you'll still have that K in the bank to spend on cars or girls or whatever.
If you get an AEG now and then try try to sell it as new in 3 years time you might as well burn your money. There are ton of those packages for sale in the classified section right now that no one will touch because either they're outdated or prices have dropped and you can buy new for less.
Airsoft, where nothing is hurt but feelings.