X-Cart & PayPal API/Parallel Payments

I'm trying to create a website selling crafts in aid of charity. Individual sellers will register with the site and sell goods. Customers will be able to add items from multiple sellers to their basket and checkout using a PayPal Adaptive Application. The application must be able to support Parallel Payments, with payments going directly to the seller and NOT to a central merchant account. I don't pay a subscription for PayPal, nor do I plan to. I do have a business account and API details. Would just need an APP ID through an [login to view URL] application once the website has been created. I've been trying to use iScripts MultiCart to accomplish this. It functions in the way I want it to, but am finding customisation of products tricky and tedious. I'm by no means a programmer, I'm much more used to the polished UI of Magento or X-Cart. At the moment I'm looking at buying X-Cart Pro for this purpose, but it does not support PayPal API out of the box. If I can get a good quote on here I'll purchase the software and upload it to my server for customisation. In addition to adding PayPal API, I wouldn't mind a slight reordering of the seller structure - namely links to the respective seller's profile from the product page. From the seller's profile you would also be able to see all the products the seller has listed. I know these functions exist, and that the code exists, because I'm using it on MultiCart. I'm looking for someone to integrate these MultiCart features into the polished UI of X-Cart.