NACHA file format script

We have a simple accounting system for our company built on PHP. We are planning on adding ACH capability. We are looking for a pre-built PHP script to hook into our software and it generates the proper NACHA files for processing ACH incoming and outgoing transfers. WE STRONGLY PREFER A WORKING SCRIPT ALREADY BUILT. If you have it already built, we would like to see a demo. Code must be in PHP. After purchase, we must fully own this script with no on-going licensing fees. If you hook into paypal or other payment systems, this is a nice bonus and will be considered. Also, if it has good "management" tools with it for internal auditing the incoming and outgoing payments, this is also a plus. If you have a quickbooks integration tool, that is also a plus. You will not be required to hook this into our software.