I'm planning on doing something a little different then yours as well, if you don't mind.
I also have a client down in south louisiana with a small freshwater tank and I was toying around with the idea of making an LED fixture for 12 LEDs of warm white and one ballast.... A quick and easy project as well.. maybe a pre-curser to building mine.
So, I have the money now to do what I want to do. I just am scared of pulling the trigger on a $200 purchase that may or may not work out.
Then again, I like experimentation and this is right up my alley.