I don't think that you can make a HPS work without the ballast, it's just way to crazy to be on it's own. As for trying to cut costs. Instead of buying HPS and MH, which are the two most expensive lights out there, invest the 200 an the kit for the HPS, and then combine it with cheap CFL's (compressed) flourescents. They have lots of blue light for vegging, and will help with stretching, and you've got a sick money light for flower (the HPS). I bought a sweet 125w full spectrum CFL for 80$ CND and I love it! And don't forget, any money you invest will just mean sweeter (and bigger) buds, and at weed prices these days, I am sure you will even out...and then some.