hydro or grow box?

growing inside and am thinkn about getting a 150w hps for two good sized plants. but then i saw this http://www.altgarden.com/store/cart.php?m=product_detail&p=653 and for the extra 60 bucks, i dont know why i shudnt get it. there has to be a downside to it though that i do not realize. anyone ever use this before and wana give me their opinion on it.

i want the hps, and its cheaper than buying the hydro system, i was just wondering if any one has used the hydro system and if it works well with growing the herb or not