Regarding the transfer of a local photography collection--if your
donor is willing, you can have a contract drawn up (with the help
of an attorney) where a certain percentage of the collection is
transfered each year to the Museum. For example, each year 10% of
the collection could transfer. Such an agreement is often very
appealing to a donor as they can take a tax deduction over a long
period of time. The contract could also include a provision for
the entire collection to transfer should the donor pass away.
Regarding valuation, I would recommend that you contact the
director of your state archives for assistance. Photos often fall
under the title of archives--a difficult thing to value.
Good luck--sounds like a wonderful opportunity!
John Handley
San Francisco