Using widgets on your current website or blog that are tied back to your Paypal account is about the simplest way to sell something I have seen. This is especially a great tool if you have one or two products that you sell regularly.
Create your own online store with the PayPal storefront. Upload products, set prices, and start selling on your website or blog.
There is a great FAQ that will get you up and running in just a few minutes.
PS - At this time, the PayPal Storefront is not available for MySpace.