If i was u ( not having any way of venting air out) i`d forget HPS or metal halide altogether!! WAYYYYYYYY too much heat for them if u can`t vent that heat out!! - i`d get a few of those ` Envirolites` they do 125 watt blue spectrums for growth and i think it`s a 200 or a 250watt red spectrum they do for flowering. They give off almost no heat and wattage/lumens/cost of electric etc etc all put into the equation all makes sense to me. I`m currently growing under envirolites and find them the best alternative to hps or mh !
OK i admitt they don`t give the same ooooooomph!!!! as MH or hps but if ur grow space and venting is very limited then that`s what i`d go for.
Seen a website somewhere where u can get envirolight 125 watt for less than 20 quid too !! very cheap!!! ( dunno what that is in Dollars for all u lot across the pond)
Sorry seen u can`t order anythin online!! must be places other than internet u can buy envirolights!!!