This is something that you need to hammer out before starting the project. If
you could sell it to others, you probably need to give the first organization
quite a price break as you'll be doing a lot of work on their dime.

If they plan on selling it to others, you might want to charge more. Also
they should tell you this up front as the design of the database could be
done differently to accomadate different organizations. For example you might
want a table with one row for the Company Name, Address, phone numbers, etc.,
so that they don't have to modify every report.

Myself, I consider the database to be the property of who pays for it. I
reserve the right to use parts of the code on other projects. For example
I've done databases for two different towing companies. I started with a
clean sheet of paper for both, but did reuse some code.