I have read the descrition. It is fine. Its a good idea. I have worked with similar projects before. I have sound knowledge with VERISIGNS payflow pro and payflow link. I can easily integrate these with your merchant account and your site. I can buid a good database for accounts handiling and for math. And regarding the buttons. I think firstly you must have the payment gateway up and running fine. I can help you in finding a good merchant account, If you need one. Finally if you like my offer please reply me.
Thankyou,Bye