Shop in Shop System (need Price-Information)

Hi,

when our shop is online, we plan (after a while) to give other artists the chance to sell their artwork on our platform (shop in shop).

That fuctions should be included:
- sepperate "seller-"registration with smth. like a contract of what the seller have to do and what we do not accept
- we (site-owners) have to authorize the artworks (to prevent junk and low-class-artworks) the seller set in his shop
- seller is able to set in his/her own products with images
- a little profile of the seller (some words of himself, garduation, picture, ...)
- we (site-owners) get some percent of the selling-price of the seller (according to the selling-price)
- seller care about shipping his artworks
- customers can give feedback to the seller

Questions:
How much that will circa cost?
How long would that take?

Hello? Anyone can give some prices?
Mh...