Question: Is it the paypal API compatible with asp.net MVC? 
Does anyone know of any expamples of how to implement it?
Thank you.

Answer: 
Recently I implemented a PayPal 'Buy Now' button in a ASP.NET MVC Razor view. In the end the button is just a HTML form that is posted to the PayPal website. However, it took me some time to find out which hidden form fields were required, and which optional fields I could also use to further configure the payment process. I have published my experiences on my blog: <http://buildingwebapps.blogspot.com/2012/01/single-item-paypal-buttons-and.html>.
There you will also find the source code for an MVC Html helper method that makes rendering single-item PayPal buttons less work.
Take a look at this site. <http://www.arunrana.net/2012/01/paypal-integration-in-mvc3-and-razor.html>   

It is specifically designed for MVC3 with Razor!