sounds a bit dodgy... all the mismatching things... paint, rims, missing stereo etc etc.. just sounds to me like he was going to use it for drift etc..
How many have you actually looked at before this one? Just be patient, it took me a while to find my 32, I had to go through many duds and the one I had my heart set on was asking too much.. but in the end the waiting payed off and the one I bought is perfect and had everything I wanted for the right price.
Just go with your gut feeling, if you think there is something slightly dodgy about the car, then there probably is..