Any old-style power-sucking household incandescent (NOT LED) lightbulb or flood (NOT spot).
IME, halogen floods may also work, but they tend to run hotter than std. household bulbs.
If you're in Cali, you may have to find a friend to buy some and ship them to you.
You can't necessarily just link to one. Finding the right bulb for your enclosure depends on many variables, and you may have to try several wattages to find the one that works best for you to acheive the desired temperatures. Once established, unless you redo the enclosure, that wattage should work from then on.