yeah Chubby is right HPS will produce a lot of heat even with a tube and fans blowing full tilt.

they have a lot of nice leds out there. Viaspectra lights I use were really inexpensive and they do the job you should look at their 1500 or 2000 versions they will do really well in a smaller space. I use my 1000 in a 2x2 and was perfect for the run. 

good luck