Dimmable Ballast Problem

In the building I work at, we have a bunch of light fixtures with 120v dimmable electronic ballasts, no low voltage. Currently they're just hooked up to a switch to turn on and off, not dim. I put my amp meter on the two lighting circuits when the lights were on. The bigger draw of the two was 7.3 amps. I believe that bigger lighting circuit draws around 876w. I've been looking for dimmers for this application, but it seems like they're not around because LEDs are more practical now days.

I guess my question is; can I use a 1000w incandescent dimmer on this application? Or is there another way to solve this problem without dishing out the big bucks?