Unless you want to spend lots of money on an acutal fuge light (JBJ makes a great one for slipping it onto the back of these tanks) the best bet is to go buy a good old 6500ish K grow bulb and a regular clamp on fixture that suits the space you have behind the tank. Cheap and easy. I was trimming my cheato every 5-7 days with this setup.
Check these out, they fit awesome back there:
Good
http://www.jbjlighting.com/prod-macro-glo.html
Better
http://www.jbjlighting.com/prod-nano-glo.html