Build an Online Store

This is a site I want to build a classified site for Selling equipment.. I think I want it to use a Magento Back end. Or maybe WP. I have found a few good themes for WP, however Im not sure the backend payment and subscription service can support it.. I would like to design a recurring payment system for the classified users giving them 30 days for $1 free when signing up. And it automatically charges after that 17.94 month after. We give them three Sites for that cost, and we also have a special financing program the Posters can use to sell there equipment. More on this.. once you are ready. So TO recap.. I need a great Classified site, Theme... and I also have two or three other sites I want to have the data auto reposted (make this note) to give the subscriber a much bigger value perception.. So it a Marketing thing sing up for the service and get three sites posting .. We list the sites, PLUS we offer your customers Leasing options to buy your equipment. Show me the Classified site that will lead the future for classified... JAY