yeah he can get 400hps easy and cheap, but it has to be consideret the space...
if tiny space or medium i recomendet the 250hps or 150 with some tiny extra lights!
because HPS lights generate much heat, so maybe 400w is too much in that space... but if not, then buy it! but with hps lights yu need good fan and ventilation!!!
HPS lights are the best grow light what yu can buy, second best is MH lights, but i recomend use HPS & MH together.
yu can get very very nice result with 150w hps too, but better with more light.
i have seen what 150w hps can do, and thats amazing!!!! never before i wosent belive that... so good luck! and nice grow times dude!