So don’t worry actually i was also frustrated with latest changes because whatever i have implemented before this changes is very easy straight forward and have proper example in Facebook developer forum but for this new changes i did not find any thing which is relevant.
With following example you can achieve Static pricing & Dynamic pricing with same line of code.
So here is the basic steps which you need to follow to achieve Facebook payment dialog and process payment
1. Create a new ASPX page i have created page with name “MyProductDetail.aspx” in attached sample
2. On this page add meta tags with and also add run at server property (if you want dynamic pricing) see below snap shot
3. Now for this page in page load event (C# code) you need to write following things according to your requirement
in brief i can say on page load event we set all the meta tag at runtime according to query string parameter which will be dynamic . just check below screen.
Now you are good to go to run this.
You can test the product URL with value in facebook debugger
whole code can be download from download code.
I hope this will help you in developing the facebook payment integration.