I have a room that has an issue with a mold/mildew smell. I know
there is no mold or mildew in this room as well as no moisture in any
of the walls. Just a smell of mold, you know that earthy smell.

I have had several companies, mold removal, come out and they agree
it's just a smell for some reason. They have offered up a solutions
where by they would use a product like a flee bomber/fogger and that
would rid the room of the smell. Of course it comes at a price of
around $400.

Isn't there something on the open market that I can use, as directed,
to remove this smell from the room?

At the present time the room is completely empty of everything.