Hi Tony,

Our company has created a module (still in final testing and not submitted yet) that essentially does that. It adds the ability for recurring purchases using PayPal Subscriptions via PayPal Website Payments Standard.

I'm not sure what exactly you're looking for, but chances are it will be easiest and most cost effective to use this module as the basis rather than going from scratch.

Feel free to PM me so we can discuss the details.

Thanks,

Jim