I found a near perfect replacement on Amazon for $2.49. Red Light 4 Pin DPST ON/OFF Snap in Rocker Switch 15A 250V AC.
If I had to do it again, I would probably buy this one: DPST Black Button Rocker Switch. The switch that is currently installed has a little led in it. It's not a big deal, but it will use up electricity over time. This switch is slightly smaller than the red switch, so I'm not 100% that it will fit perfectly.
This is a pretty boring post...but I hope that it will show up if anyone needs to fix the power switch of their heater. It was super easy. The wiring connections were exactly the same as the switch that was taken out. And from the look of it, broken switches are not that uncommon on these heaters.