Build an Online Store -- 2

I need a subsite to local community buy and sell their products such as garage sale items. Seller Requirement: 1. People can login 2. Upload their product details (such as item description, price, etc) 3. Seller can update their product description/price 4. Add seller contact number Buyer 1. Buyer need to log in for buy 2. They can add product to shopping cart 3. For pay, promoted the people to our PayPal site Site requirement 1. Product category 2. Simple internal search option 3. New product comes on top It could be simple site because it just uses the local community. The site should build in Drupal. We already have a website. So the new subsite housing on the same site as a subsite. 1. Please let me know the price of the project 2. How long it will take to finish this project