I would go with MH. 3x250 HQI mini pendants. Bulbs from Light Spectrum Enterprises are 25 bucks, and would only need to be replaced every 1 1/2 years. The life of a is about the same. When you overdrive the bulbs, which you would want to do with them for clams, the bulbs life gets cut in half unless you can keep them VERY cool.

Or you could try and go the LED route....