I sent out 1700 post cards and spent nearly 700 bucks on them. They have got me VERY few calls. Literally probably 3-4 for things I don't really want to do and aren't very profitable.
I put out about 600 door hangers. I think they were 100 bucks or so. I have had significantly better success with them. I have had twice as many responses as I have with the post cards.
My city has a facebook buy/sale/trade page. I posted our post card on there and it has had much better results than paying 700 bucks to have them sent to a big part of my city. Thinking outside of the box a little can be profitable.
I have tried craigslist. It has not given me many if any results.
A lot of people contact me through my website. Having one is very beneficial even if it isn't very exciting like mine.