Solar attic fan - one more chance to make this work

SooooooOOOoooooo......

We've recorded a high temp of 117 in the attic.

The landlord nixed the continuous ridge roof vent.
The landlord considered a solar attic fan.
The landlord *bought* a standard fan.

Then The Most Wonderful Partner Ever found out the house already has a fan!
But.......

doo doo-doo doooo!

..the motor's dead!

Yay! You know what this means, right? If we can find a DC motor and compatible array we could reuse the existing fan *and* it could be off the grid.

Landlord said, "I'm going out of town for a week. Do what you need to to get the motor replaced or working and I'll reimburse you."

Oh-Ho-Ho. Now is that wide open or what?!

So I need to know where I can find a compatible motor/solar array. Landlord will not want this to cost much more than $100, I'm sure.

Can it be done?
Help!