Like Orion, I have gone down the home made path.
I have hade up a number of eyepiece heaters (2" and 1.25") and an objective heater for my 70mm refractor, using a "ladder" of 470 ohm resistors, adhesive backed closed cell foam double sided mounting tape and velcro. Cost about $3 each tops including the RCA jack. I have also made heaters for my Telrad and Quikfinder units using several resistors encased in heatshring tubing for same cost.
In my solid tube dob there is no variable heat control, that is when pluged in they are on. In my string truss dob I have used a PWM unit to provide vairable heat output. I have to confess I think I went a little overboard with the stringscope electrical panel
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Photo's below.
Cheers,