Without more info, it seems you are in the right price area for a'private party' sale. The bottom line is the 125,000 miles and how well the engine was maintained. it would really stink to buy the car at $10,000 and then have to put serious $$ into it, because it would be money that you never could get back if you needed to sell in a hurry. Also you didn't mention how many owners or the title situation, Carfax, etc.. which all can influence pricing as well. I don't know if I am pricing a one owner, highway miles, well maintained car or a 5 owner example in which the last owner was a teenager who terrorized his neighborhood for the past 10,000 miles. I know which car I would pay $10,000 for and one I wouldn't even bother with for $5,000.
2001 Trans Am Convertible Red w/ taupe top (A4)
2007 Ford Mustang GT/CS Convertible White w/ black top (5 speed)
1974 AMC Matador X Red (3 speed auto)