Go to the dollar store or similar store, or look at 'appliance' or 'heavy duty' or 'specialty' bulbs at some hardware stores, incandescent can still be found rather easily as the law only outlawed those that were used for consumer general service illumination... MANY other uses for incandescent are still permitted in the US the most common exemption being used is the 'rough service' one, basically just some extra wording on the package stating the bulb is for rough service use, not general illumination...
If you want a thermostatically controlled one, $8 water heater thermostats work fairly well and are easy to get locally, they work fine for 110-120v as well... Should be good to over 2000 watts @ 110-120v... Forced air over the back of these thermostats really helps them regulate the temp better, as does drilling a few extra holes in the housing as found on an
Ebay video somewhere... Just splice one wire to the bulb...
https://www.menards.com/main/plumbi...4452231334-c-8689.htm?tid=2321399033828729931
Or hit up
ebay and get something like this, and get a cheap 12 volt wall wart to power it...
http://www.ebay.com/itm/331577078605?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
The relay on the above is good to about 1200 watts @ 110-120V, all you need is a 12v wall wart to power it and splice one wire to the bulb...
I much prefer a metallic heat element over a light bulb because constant cycling on and off will shorten the life of the lamp and it will fail at the worst possible time.
To solve this you can simply run two bulbs in parallel, if one blows you still have a backup.. And I advise people that do go this route to use two different brand bulbs or install them at different times, because there is a risk that two identical bulbs installed at the same time could go out at nearly the same time...
Or as you said there are other types of heating elements, PTC is nice because they pose little to no fire risk...
