My rate is $300/hour. I usually can provide an estimate for a migration, but not until I’ve seen and done some tests on the database. Even for a well-maintained import script, it’s not uncommon for their to be site-specific issues (plugins, strange formatting habits and expectations of the community, and a bunch of other stuff) that make importing a particular database troublesome.
If the database isn’t too big and the changes are not too many $1500 is a wild guess.