BARGAIN - addon like NEGOTIATION - part 1

an add on for CS CART MULTIVENDOR the vendor would have a set price for a product with his readiness to negotiate. the customer can offer a price, that will get automatically accepted if the price is above the maximum price set by the vendor, if not, the vendor can reject or give an counter offer, that would either be accepted or rejected or countered by customer again. the offer can get autorejected if its below the minimum price set by vendor. So the vendor will have to set a minimum and maximum price. example : ebay has that feature called OFFER