People usually balk at the initial cost of the DE light, but I suggest you do the math on the long term affordability of them. If The Aqualine or Giesmann's are out of reach, have a look at the Hamilton fixtures. I've got a single 150w over my sump that was 6 or $700. (you can probably find it a bit cheaper than I did, too) I know it's available in 250w, but I don't know that price. One feature about the DE's (double ended) bulbs is that they have to be replaced less frequently. If you get one with an electronic ballast, it will use less electricity than a comparable tar ballast set-up. Also, with identical reflectors, I believe that watt for watt, the DE's will out perform the mogul based versions.
Food for thought.
Mitch