ecommerce with affiliate / coupon system?

Just wondering if anyone knows of an ecommerce plugin/solution for WP that allows clients to pay with credit card (quantum gateway) and paypal. Plus has an affiliate tracking system and also works with coupons/promo codes. There are only going to be about 20 items on the site, so it doesnt have to be that robust. I will probably end up just using opencart, but wanted to see if there was a solution that would allow me to use WP.