In association with Plimus, we are happy to release a plugin that allows easy WordPress integration with the Plimus payment gateway.
Plimus for WordPress relies on Plimus IPN (instant payment notification) to provide real time reports about your sales. It can also automatically register new buyers as users on your blog which allows you to for example use membership plugins.
In a recent ecommerce provider comparison Plimus was found as one of the most cost effective ecommerce providers following Google Checkout and Paypal. We are using it for managing sales for SEO Smart Links and it has been great so far.
Click to check out Plimus for WordPress plugin.