Yeah the part about not having the title in hand makes me think twice. The guy lives in my sub division. Selling a 2005 Jeep Sport looks very clean, paint very little wear, lifted, new tires, 1 y.o. top, aftermarket front & rear tube bumpers, 90K miles, inline 6, automatic. $11.5K He started at $13K and from my search most 2005 are $14-15K.
The DMV has a guide that gives the valuation for calculating the tax. You can find it on their website so you know before you go in. In my experience, their valuations have been very low.