I just bought a 97 4 Runner Limited from a dealer 78K. I have no idea if the timing belt was changed. How much would it cost to have a mechanic check to see if it's newish? Should I go to a dealer or just a Midas-type place?

Don't bother. You can assume it was not changed since it doesn't need to be changed until 90K.

Come back and ask when you're at 90K.