crested geckos and other rhacodactylus dont need heat or light if there is enough ambient light from a window. they are understory species, so the forests of new caledonia (where rhacodactylus are endemic to) allow only some light to penetrate below the top of the canopy.
I am a university student, so I am also interested in keeping electrical costs to a minimum. heat pads are great fro animals that can thrive on them.
the pure and simple truth is rarely pure and never simple - O. Wilde