N2ri mentioned way above that an easy-bake oven reaches hundreds of degrees with just a lamp. That got me thinking. What would a 60W spotlight do to help heat the inside of the printer.
So I figured, let's find out!

First, a little bit of background. I have installed insulating side panels on both left and right side and found a sterilite tub that fit perfectly over the top of the printer (just cut out where the filament goes in) and applied weatherstripping along the bottom of it to form a gasket. It's just lying on top, not fixed down yet.
I use a kitchen temperature probe to attempt to monintor the temp inside the chamber. Since I am mainly interested in the temperature around the build platform, I taped the probe to the back wall of the Z axis. Now, the probe will follow the build platform.

Finally, I took a 60W work lamp and have it sitting pretty much right inside the printer to preheat it.
It did manage to raise the temperature around 13 degrees C after nearly a half hour. Not nearly as effective as I had hoped.

However, I did learn a few things. One, it makes sense to mount my probe to the Z-Axis since that is where things are the most important. Second, an incandescent lamp does not heat the air as much as one would think. They make special heat lamps for that (like the easy bake oven uses.) And third, my chamber heater might benefit from mounting on the Z-Axis as well.
So, here some ideas... (this is a 24V system)
Two 2.4 ohm power resistors mounted in series as a heater. Tap off the center to run the 12V blower fan.
Use a heater cartridge like used on extruders and assemble some custom radiator
Tiny halogen lamp as the heat source with radiator and blower. Second advantage is a lighted build area.
When I was experimenting with different ideas, I found some nice little 40mm blowers that are very light and quiet. If I can make this heater compact enough to mount on the Z-axis and blow the hot air onto the build area, that may perhaps be ideal. I think I could fit the entire affair inside of an altoids tin.
Thoughts? Power resistors, heater cartridge, or halogen lamp?