Environmental controls?

So my current set up is outside, and it has been really cold lately. Soon, though, its going to be in that weird spring-y inbetween time where its hot somedays and cold on others. I have a little space heater out there that does a good job, and a big 8" fan exhausting air out of the tent, but I guess I have 2 questions.

1) Once its summertime, and it's like 100 degrees out there, the most efficient system I could install for cooling would be a little window AC unit, correct? Or would the $300 "portable air conditioning" units be more effective? and

2) Are thermostat-contnrolled timers an easy solution to turning on and off heater/AC/fan combos? If so is there a good reliable brand people can recommend? I have seen some around $80 but would like feel like they're going to be what I want.

I haven't gotten as far as co2 and humidifyer yet so I don't need one of those $1000 everything-in-the-grow-room units but is there a good sweet spot?

Clarify the situation and location of your grow. You say it's outside but then mention a tent, space heaters and AC units.

Outside as in, in my garage in a tent. But in an unheated, uninsulated garage so the temps vary a ton. As opposed to my bedroom, where it was last time

I struggle something terrible with heat in my space, which is in an extremly well insulated room above the garage in a polebarn. Its actually 2 spaces, the big one is 8x14, with 3 1000's in there aircooled. I use a dual hose portable ac by whitner, it works ok. But in the summer, its still 90+ in there sometimes. I use co2 so its ok, but without it, i'd be screwed.

Its this one...has heat too.....