they do make a conversion bulb for a 250 watt.. i bought one about a year or so ago.. its an eye hurtilux brand, and i think it ran me around one hundred bucks for it.. you are right though, not many companies make conversion bulbs for the 250 watt, i really had to scour the net to find the one that i bought.. most companies only go as low as maybe six or four hundred watt bulbs in the conversion style, but eye hurliux makes the conversion bulb for the 250 for hps for an mh ballast..