This question has been asked before (link) but I have slightly different requirements. First, I'm in Canada so that rules out Google Checkout and probably a few others. I just need a basic service that provides "Buy Now" functionality, no shopping carts or anything like that. The site isn't super high volume, so I'd like to avoid any site with crazy monthly fees. I also need the ability to setup "discount codes" (or whatever you want to call them) for special promotions. The site must also have some sort of payment notification service (IPN). I am currently using PayPal, but their lack of discount codes is really starting to restrict what I can do.
What have you used, or what would you recommend I investigate further?