You just have to find the right buyer for the car. I am very familiar with this.
I used to own a 1995 TBird LX V8, bought it for $2,000 with 64,640 original miles. A year and a half later and about 2,100 dollars in repairs, with 76,500 miles and a Ford Nationals award, I sold it for $6,300 (more than twice blue book value according to NADA) in March 2011. I put it on my local craigslist and it sat for 3 weeks on there, first person who called drove out in their 97 Tbird and bought it right as it sat.
Fast forward a year. I purchased a 1987 Ford Escort GL hatchback from a little old lady for $50 back in December 2011. Yes, $50. It had 40,920 original miles. I put another $1,800 into it with repairs, Escort GT spoiler/wheels/fog lights, lots of elbow grease, and a second place award at Ford Nationals in Carlisle. The car was spotless but it was still a Ford Escort. Put it on craigslist with 52,275 miles on it this past November, sold it in 3 days to a guy in New York for $3,500.
People call me the wizard since I always find that one buyer who wants what I'm selling. I always start my price high since I never 'have' to sell these cars, but I like knowing the market just in case I need to sell. I also make sure I keep every reciept and document for the car including sales brochures, window stickers, etc.
The same day I sold my Escort I drove to Ohio to buy my 90 SC with 38,800 miles on it. I saw it on craigslist. I now have 41,200 miles on it and I use it everyday. I have snow tires on it and although I keep having to repair random things on it, but at the same time I love TBirds and I don't care if I have to dump money into my SC, I love it too much to let a low mile example go neglected.