Get a plastic storage container and put a lamp inside.
Seriously, it works perfectly and you can get an led light-bar if you want to upgrade in the future. Put a layer of wax paper on the inside to diffuse the light if it's too uneven.
OR you can pull an old computer monitor apart, take the LCD out and then put it all back together (leave the backlight in). Now you'll have a more or less even light source with brightness controls if the monitor had them and you remember the buttons just put a piece of glass over it and you're all set.