The original inspiration for this is Tinkernut's project. (Gerd Lobmeyer, Open Green Energy and others have done similar projects.)
I'm thinking of pulls from old mobile phones, esp. Nokia. Power use should be minimal. Availability (used) should be good.
What's available? Again power consumption should be small when backlight isn't used. Looks like finding something suitably sized with workable I/O connections is going to be difficult.
What's the power consumption?