I know I went all over the lighting section and I asked 2 different employees.
The only dimmers they had were these one touch dimmer things that didn't look like the dimmers I had seen online or seen others use, not the ones with the slide you choose a setting on. They kept trying to sell me a wall dimmer even as I described what I needed.
I went to a petco and they didn't have one.
I feel like such an jerk. I though my ultratherm was so low watt it would hold 90 under a cage and substrate. but when I let it run for a half hour brushed back the thin layer of substrate and scanned it it was 133 degrees! Needless to say I unplugged it.