i would recommend u use envirolites m8 as it's a bedroom grow.
They work great, cost fk all to run & won't give u the heat problems of hps.
Hps is not a good plan if u intend storing incandescent material nearby (clothing)
saw a great cost calculator somewhere - I'll post it up if I can find it
http://www.ukpower.co.uk/running-costs-elec.asp - that's UK btw but I'm sure there's something similar wherever ur from
btw u would stunt the growth of ur plants if u put more than 4 in that size space m8 - give them room to breathe!
Even then, u would probably end up scrapping a few after sexing, but u will be surprised how much room just
1 plant can demand.