Actually, that's just the sort of thing I'm interested in. I'm helping with a small local blog (
http://davidsonnews.net), and we'd like to have a bulletin board where local people can advertise garage sales, and so on. Your site would be perfect for that, especially if you could set up a custom page just for our town.
That might be a good way for you to proceed -- find small local sites and email them, offering to make them a customized classified ad page. A lot of towns have web sites, either operated by the local government or by independents like us. We're not big enough for Craigslist, so you'd be filling an important niche.
Make sense?