Lots of air flow, and a climate controlled a/c unit. If you are going smaller, perhaps just make sure your house temp air get pulled into grow room at an alarming rate. My room is filtered about every 60seconds, that seems to keep the air temps down. In my little grow cab, I have air cooled lights as well. If you dont get good cooled lights, you are fighting a very tough battle. Until I spent the $$ on a big ass fan to suck air out of the room, I was fighting heat badly. Now, I run 4x's the wattage I did, and keep a steady 76deg.
Hard to buy everything you NEED at once, unless you spend a ton on the good stuff. Perhaps start with the lights you want to run, monitor temps, and purchase air handling equipment accordingly. Dont forget odor control