AH supply and/or spiral compact fluorescents are the cheapest way to go. Basically, AH is you higher quality option, but if you need more heat, slightly less light, and more money in your wallet, then try to go with spiral compacts. Otherwise, I use ODNO with success.
I've always been a big fan of power compacts. However, recently i've just been using normal flourescent shoplights from home depot with plant bulbs (same bulbs are cheaper at wallmart than HD) and they've been really nice (and cheap) knock on wood. Think it all depends on the height and length of the tank as well as what kind of plants you're looking to keep.