246323 Etsy Clone with Extra Features

We are looking for a clone of etsy with a few differences. We like the look and feel of etsy but would like it to have its own similar layout, but not identical. This would be a multi-user platform, where people can sign up to sell their items for a set price. I would like there to be a function for another user to make a 'best offer' if they do not like the listed price, and for the lister of the item to be able to accept, reject or counter offer. We need a feedback system in place, as well as a private messaging system so users can contact each other with questions. A forum would be nice, but not 100% necessary. Users would need to register a credit card or paypal account for their listing fees to be taken. Also, when a user sells their item, the buyer should be taken to paypal to complete payment. Ideally, the clone should be able to recognize that the payment has been made. As far as the shopping aspect, it is important for us to have drill-downs - for example suppose we have a category for band merchandise, the shopper can first choose the band name, then the product, then color, size, etc. (see below) - Rolling Stones - - T-Shirts - - - black - - - - XL BUT, the drill-downs don't necessarily need to be in that order. If a person wanted to shop for all BLACK t-shirts, they should have that option 1st, or if they wanted to shop for all XL shirts, they should be able to choose that first. (I hope that makes sense!) We need to establish a listing fee & a final value fee that will be assessed at appropriate times. Users should also have the option to easily renew their listings. Standard listings will be active for 15 days, we want them to be able to double the original listing time for a slight discount. (For example, you can list for 15 days for .30 or 30 days for .50) And we would also like to have featured listings available to users for an upcharge. This means they would be listed on the front page for a block of time for a set fee. Finally, we would like to have an option to easily add some sort of advertising to the site. We aren't sure that we will use this, but maybe!