dj00140 ,yes you can get a conversion bulb.

I went to purchase a MH>Hps conversion bulb and for me it was not cost effective.
The spectrum was a little different than I wanted and the cost was over 1/2 the price of a complete 1000W HPS system.

I shelled out for the whole system, about $200. A friend spent that on a hi-end conversion bulb.