I just bought a 400w HPS with ballast and reflector for $120 on ebay. For another $30 I got a Metal Halide conversion bulb for vegging. I think the best bet is to get a HPS conversion bulb that will work with your existing MH Ballast.
doco Reviewed by doco on . HPS light system If u buy just a 400 watt hps ballast what else besides the light socket do u need to get kit runnin? Rating: 5