Posting a Rental / Apartment Ad on Craigslist

Now don't get me wrong, I do post advertisements for my business, Apartment Finders, on Criagslist but is that housing search getting rediculous or what? It seems my competition is posting just about every other minute and now even apartment communities are starting to post frequently. Because I track the visitors to my website I do know that posting has an effect, but how much? With all the spam on Craigslist, are many renters searching the available housing anymore? I know it is still a very powerful, free marketing tool but I am thinking now that I would much rather have Craigslist charge then to have it so difficult for a renter to find what they are looking for. If Craiglist simply charged $25 a posting, like their job postings in Arizona, then maybe the spammers would lay off and I would not have to be one myself to compete. Think about it Craigslist owners, more money for you and less Craigslist housing SPAM. Sounds good to me and terrible to my competition!