Hi Eric.
SharePoint is not required for InfoPath but from an enterprise, best practice standpoint you typically want a client server setup and have a central repository for your documents or some central control or process which governs their use and movement.
I would recommend you investigate the Database Accelerator Web Services Suite. It can provide what you are looking for, including the ability to have infoPath forms in a browser for a fraction of the cost. It also provides a platform for enterprise electronic document solutions.
Qdabra Database Accelerator Suite Version 2.0 - Developer
If you would like to see a demo of a solution built on this technology let me know.