I have been an advocate of Govdeals.com for a while now. I recently purchased a 2007 Crown Vic, In perfect condition with 76k miles for $2600 to use as a backup car. We have two families living here mine and my daughter lives next door. I like to have a backup car. So now I can call for backup and get a real popo car. but back to the subject, I see a few boat motors on sale in West Columbia lately. if you need a good used motor some of these might have potential. Always ask for the mechanic and ask him about condition, known issues. The nice thing about Gov auctions is they are usually always honest about condition.
In the case of my popo car. The mechanic told me it had overheated twice and the chief did not want to drive it so they sold it. all was wrong was a thermostat gasket that they had replace once and did not suspect was still leaking. sometimes you can find a deal. But just ask a lot of questions until you feel comfortable.