Icecap's are nice but way overpriced. Unless you really want to use the dimming feature, I would go with Fulham Workhorse ballasts.
As I said in another post,
Aquarium Hobbiest Supply has great prices on PC retros, and they don't skimp on the reflectors. A 4x96W kit runs $215 and would be similar to what you are considering. (AH will supply two 220W Fulham ballasts for a total of 440W, same as the Icecap 660.) For $299 they sell a 6x96W retro that should let you keep most anything short of SPS and clams. Those prices include everything you'll need, too. Bulbs, endcaps, ballasts, cords, even screws and wire nuts! If $300 is your budget, that would be a good way to go.
Another note: There are guys on eBay selling 6 packs of 96W PC bulbs for $40-50! That's a bargain!!