Auction like dubli.com based on spreecommerce

I am planning to develop an auction system, which should be very similar to the idea of dubli.com. In short: Every auction user need to have an account with a balance on it in order to be able to view the prices of the auctions. When a user decides to view the current price of on of the offered products, he pays an amount which is subtracted from the product price. after viewing he can decide whether to buy or not. See the explanation of the system on [login to view URL] I am still in a very early preplanning phase of the project and your first task would be to create a roadmap for the project with me. :) Reqs: * You should already know the structure of spreecommerce and you also should have some extensions for it in your portfolio. The final budget depends on the roadmap. :) Well, if you are interested in this project, post here. I will be glad to response. Cheers