We are planning to purchase a high speed document scanner for sig cards and eventually loan files. Any recommendations for a good one?

Assuming you're working with a vendor to provide the indexing and retrieval interface, I strongly suggest you work with your vendor to decide on a scanner.

If you're not working with a vendor, how will you create the indexes and retrieve documents?

We have 2 cannon 3060 (mid range)scanners that have been doing an excellent job for about 3 years. We scan to a TIF file which is what our core accepts for attaching (signature and loan, ect) files.