In fact there are many Internet evergreen success model and one of the top most of this type is Internet classifieds website. The most important reasons supporting this is the fast rising Internet usage and online e commerce.
Few months ago i launched a classified website for Used Mobiles and with in 2- 3 months it is listed in the top 500k websites as per Alexa and at-least it gets 300 -400 unique visitors daily. I used the classifieds ads script from appthemes. Even starting a classifieds ads website for a city has good chance to become a huge success due to the rising online needs that is niche specific.
How to monetize you classifieds website
Basically you should only try to monetize your website post you have quality, sustained traffic on to your website. Once you have this there are different options to monetize your website. you could use any of the below earning source as per your choice.
Membership fee to join classifieds
Craigslist model: ads posting fee only for specific categories.
Membership fee for visitors to contact advertisers
Banner / Product advertising fees
Take Home: So if you have an idea, do not wait. Start it off and you could find success soon if you don’t have much competition as of now.