Hello My Friend,
I think your idea would work in larger cities. It definitely has potential because people need to know what apartments are available when looking for a place to stay. I also like the fact that you realize it's better to offer your service FREE until it has proven itself as a viable alternetive. There is alot of apartment rental magazines in my area and if they are making $$$$, you can make $$$$$ with a web-site.
However.....this business is 75% off-line, which means you will have to beat the streets to find advertisiers. You will need more than just signs to find sponsors.
This idea has potential, but you'll never know until you try it!
Good Success!!!
Vondre'
The "BIG BRAIN" Entrepreneur!!!
Sell Computers To A Hungry Market!!!
http://www.sellcomputerslikecrazy.com