well in the veg stage you really want to use a fluorescent light it is the best becuse with the hps it gets to hot and can burn them... the fluorescent light well not burn them becuase it do not give off that much heat... but if you want to go and buy that fluorescent light it is about eight to fifteen dollars for the lamp and then it is about five dollars for the light that are made for plants... if you want to do that then place the lamps 2 to 3" away from the plant becuase if you don't it will cause it to grow really tall and reach for the light and the stems will be weak and not be able to grow big buds... the hps light are better for flowering becuase the light dosen't have to be as close becuase it not growing as much it is more flowering and it needs more heat and the hps lights give off more heat.