86 ae86 for 500$

Okay, I'm new to the ae86 game so I could use some help. I found a 5 spd. 1986 2dr hatch bk. with bad paint, good int. no rust and it runs good. The mileage reads 65k but I don't believe it. The guy wants 500$. Should I buy it? Also, how do I know if it's a gts or not. Thx.

It'll say GT-S on the side and/or rear.
You won't find a GT-S for $500 unless it is from a junkyard or a grandma.
You are looking at an SR-5.