Netbilling rocks. We use them for membership and for hard good sales.
If you are looking to sell videos and what not, you do not need an adult merchant account. All you pay is a small setup fee to the bank and a small setup fee to Netbilling. I think you can do it all for under $200.
If you get a nice shopping cart you can use netbilling's features as the gateway and set it so the surfer never even sees the netbilling interface. This way it looks more professional on your end. (you will have to setup SSL though)
When we converted Georgia's store from using pay pal on regular html pages to a professional shopping cart with a built in affiliate program, sales quadrupled. Netbilling will process more sales than third party processors and it gives you more control over what you can do with fraud and security.
If you need more info on shopping carts, please feel free to shoot us an email.
Sweet Georgia's Store
Mike