Looking for Plugin to connect quickbooks/bill pay online with PayPal

I am developing a WP site for a client that current;y using Quickbooks for their invoicing. They would like to have where their customers can go to their website and pay their quickbooks generated invoice online. Enter in invoice info and process payment with PayPal. I have searched everywhere for something that will help and is free or very low cost (client is just starting this business)

Any help would be appreciated.