Sounds like it's time for a little Guerrilla marketing campaign!
The resources that first come to mind are eBay & Auto Trader (autotrader.com). You should definitely maximize your free web exposure as well. As mentioned, a craigslist ad would be a no-brainer.
There are a ton of other free auto classified sites out there worth submitting ads to. Here are just a few that I have bookmarked:
http://www.excellence-mag.com/classified/submit.html
http://www.pmletter.com/
http://www.porschatrader.com
http://www.porscheclassified.com
http://www.roadfly.com/porsche/classifieds/cars
http://www.autoexotic.com/temps/index.cfm
http://www.motoclassifieds.us
http://autoexplosion.com/cars/sell
http://autos.yahoo.com/used-cars/sell_car
http://www.usedcarpark.com/cars/sell
I'd probably stick it in the local PCA mag/website as well.
Good luck!