Workhorse Ballast - $20
Lamps Clips/ Endcap - $5 to $10
Heat Resistant Rubberband - $3
Bulbs - $20 to $30 each.
Reflector - $20
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Or keep it simple and buy an Helio T5 Clip Lamp. They're only Normal Output so maybe get the actinic, and replace the 50/50 PC with 10K once they're old. Here's my 36" T5 Daylight Clip on Lamp: http://uweb.txstate.edu/~xp42012/misc/t5_helio.jpg
My 36" T5 cost $25. I've seen 48" for $27. And I know they have them in smaller size too (probably 24".) Taxman have the actinic Helio T5 on his tank that you've seen. You can daisy chain several T5 Helio together when you buy their extension cord. The reflector is puny (hence my suggestion in your other thread to paint the inside of the canopy with a marine environment water proof white paint. Some people say using this type of white paint as reflector work better then using the polished aluminum reflector.