Where to get a replacement switch (potentiometer)

I found a site that wants $10 for the telrad switch. But is there a cheaper source for electronic components (one that maybe doesn't refer to the component as telescope equipment ?

Just do a search for a rheostat of the proper Ohm, you will find quite a few hits.

Tom, I have made several LED dimmer circuits from an article in Sky & Telescope. The circuit allows dimming with very good control over the brightness range, much better than just a pot. The article is titled "Dark Sky Meter" February 2001 page 138.