If your GB stated $290 it should be $290 and nothing more regardless of power consumption. Those were the terms the customer agreed to.
Be sure you review the timeline .. $290 for 3mo or 6mo. Now it can be 400mo if you want to renew. I know several data centers which want to fill their racks with a lower monthly rate for the first months. If you keep the stuff there it will eventually flatten to a rate where they are getting a profit. Usually they waive installation fees just because the profits are made when the units are running there and no one looks at them.