Ask HN: Is this idea worth my time?

One of the things most web apps have in common is that they do not accept payments by anything other than debit/credit card. I've been considering developing a service that would allow payment by bank transfer in response to an invoice. Basic functionality is:

* Invoice sent to customer on a frequency selected by user * Payment made directly to user with remittance advice sent to email address generated by my service. If email can't be used, I propose using a service that scans hard copy mail. * Scan emails and attachments for unique invoice number and when found post back to user's application that invoice has been paid

It's a fairly non-trivial application so thought I would solicit some feedback on the idea.