i have recently located a bunch of 2002 svt's around my general area. one in particular bout 11 miles from my house. i went test drove it and did some numbers on it. Turns out i go in to negative equity on a trad ein and the payments go up like 60 bucks more than i want... is it safer to go through a dealership or purchase one of this site...if off this site how do i go about purchasing one? do i make pyment s or cash upfront? how does this work?