I realize the Portfolio is not an ecommerce platform. However, it would be very helpful if users were allowed to embed html code. That way I could embed something like a paypal button to accept payments
The best you can do is create custom Portfolio pages with outbound links to your 3rd party shopping cart. Many online carts support PayPal as well as other payment gateways which gives shoppers more payment options.
Etsy to name a few
Nancy O'Shea, Adobe Product User & Community Professional Alt-Web Design & Publishing ~ Web : Print : Graphics : Media