Freelance Project

I am running phpprobid auction software you can see it at phpprobid.com I am in need of a shopping cart system for my members who will be running stores at my site. Currently my auction site is setup like Ebay, when a member makes several purchases from one seller this creates multiple orders. This can lead to many expensive paypal fees. I want to have some type of shopping cart system setup so that store owners can run their store through the auction site similar to a regular online store. 1. Buyer selects item for purchase and the item is placed in the shopping cart and can continue shopping and adding items to the shopping cart. 2. when the buyer is done they will complete the order like normal through the auction site however all the items will be paid to the store owner in one payment. Right now the seller has the option to setup 2 types of auctions. 1. Standard auction with option for buyout 2. Dutch auction is where the seller selects the quantity and price and the buyer selects how many they want to buy at that price. This system would have to block items from multiple sellers being put into the shopping cart. I want the shopping cart to work with Dutch auctions so the store owner can run his store like a normal online store if he/she wants to run it that way. With the current features I don't think this will be to complicated. The system is already setup to go to the checkout process when 1 item is purchased, it just needs to be able to add multiple items together and make one payment at the end of the checkout process. Please let me know if you have any questions, I am sure I am making this sound more complicated than what it will be. The coding is in php.