DEVELOP ADD ON FOR CS CART MULTIVENDOR VERSION 4

We have our website based on CS Cart Version 4 multivendor. we want to hire someone who can develop or has already an add on with feature called " OFFERS AND COUNTER OFFERS" ADD ON FUNCTIONALITY the idea is the buyer can place an offer , or counter offer to be accepted or rejected by the vendor the time frame is just 3-4 days features like 1. the vendor can mark, he is ready to accept offers 2. the buyer can place his offer value, to be either accepted or rejected or vendor can send a counter offer. and similarly even buyer can accept/reject/counter the new offer kept by vendor 3 feature of auto rejection can also be set up 4. a maximum 3 attempts can be given 5. auto mail, and the vendor or buyer is send to show an offer , counter offer or reject or accepted EXAMPLE : u can see the similar functionality on ebay.