I was ordering an Iwasaki bulb, but the LFS was having some problems with the order. Since my corals were dying, they sold me the Helios bulb at cost - which was well under half the retail price.
I have seen some test results from Sanjay on reefcentral that show 250watt helios bulbs have PAR ratings off the chart. The prices are a little high...maybe why they aren't as popular