Fulhams really are the way to go. V-HO lamps arent cost efficient and icecap ballasts arent backwards compatible with only HO lamps.
Fiddling with different reflectors and such will end up costing you more but once you find the style and design you like you can replicate it for cheaper, potentially. IMO, the design and quality of the badboy is just hard to beat. Sucks that its so expensive, and that I want/need 4 for every 4'x8' grow space I have.. The more lumens on the colas, the better. Gotta really keep them lamps close for it, and at a 95 degree operating temperature with a clip-on 6" fan that works wonders for air cooling the lamps.. its just too hard to even think about beating.
Still, building your own fixture may be great for side lighting. I think the deal that you can get for RADIIONs with lamps included (and your choice of lamps at that!) is a great deal even if they arent the fulham ballasts, they do work well for side lighting.