my space is about 5'L x 3'6" W x 7' h. had the same problem when i started. this is what i did. fans fans more fans and then just one more for the hell of it.
my temp now is 65f - 70f lights off. 74F - 78f on. before it hit 110. its a 1000w hps
first thing was the hood $110
a lot like the one someone posted before. i bought a 6" inline duct fan $25 from lowes
there is a dryer vent running from hood out the room to the inline fan like this
now take note that these inline fans only produce the CFM stated on box if its a straight vent. the flex vent restrict air flow. that was not enough for me because its a 1000w. so i bought a $3 fan and did this
now in the summer i will replace the fan with a vent connected straight to the ac duct 1' away. then i found this really cool fan that has a thermostat on it.
i placed it in the wall at floor level. (i built the wall so it was easy) and then i added these fans
this is probably the first thing i would do i move the ballast out side of the room.
hope this helps. i spent way to much time killing plants to figure this out and not share it with someone. also if your room is smaller then you can do it on a smaller scale. they have a 4" inline fan was like $12. watch out which hood you buy. pay attention cause some of them dont come with the glass, which IMHO is a rip off.