HELP ASAP!!! Need to buy some gear!!

Hey all, first time posting here.
I am a legal ommp grower with some questions for you grow room designer experts!
Now in the state of Oregon patient/growers are allowed 6 mature plants and 18 vegetative plants per card. (Currently running one card)

Here is the run down. i have a room inside of a room inside of my bedroom...venting is difficult you could say.
I just got my taxes back and need to make an investment for the summer weather to come.
I have 2 600 watt HPS in a room that is 4'(wide)x8'(long)x11'(tall) inside of a room that is 14x14x11.
and i have a tent inside of that room that is 2x4x4 with a 4 foot T5.
As you may assume the big room is flower and tent is for veg.
I have a can fan in the flower room that vents through the hoods and sucks the air from the flower room into the big room.
and the veg tent just has a fan blowing the heat out the top and sucking air in the bottom.
and the big room door is open during the night when lights are on and its shut when lights are on.
during lights on I have my bedroom window open and a box fan blowing air from my bedroom into the big room

NOW HERE IS MY QUESTION TO YOUS GUYS!!!
This is my entire set up! its a pain in the butt sometimes. I want to make my room more efficient!
SO i am looking into buying a portable AC for the grow room. but i havent really much experience yet (just had my 4th harvest).
I dont know the PH of my water or soil. i just use a few drops of PH down every time i water.(FF happy frog soil, GH flora series with blackstrap)
And my harvests dont seem as abundant as i see other growers with the same lights as i do and HUGE plants.

So im torn between what to buy!!!! HELP!!
and AC?! or CO2? or more lights? or a PH meter?

I have about a $600 limit and my plants are lookin like its getting hotter every day.
So what should i invest in to improve the yield of my ladies?!?!

Any questions, comments, or Q tips are encouraged ASAP =]
thanks!

would think in terms of first aid. Ph monitor, Ac, as teses things can save your bacon and the others are icing on the cake

but what kind of AC. i see people saying dont buy a portable cause they're crap. but i dont have 1200 to spend on a mini split ac. i just wanna make my girls big and happy.
=]

My vote is at least for a ph meter.

/c units with no problems I got mine used on ebay for $100 delivered but they run about $300 at homedepot. I never heard anyone say they are not godd but if they did they are nuts. You just have to get the vent house out of the area of the room your cooling. Mine can cool an 8x8 room in 90 degree summer weather to 68 in about an hour....Mine also has built in dehumidifier or humidifier. Just set humidity level and it will do whichever is needed.

I think i may get this http://www.bestbuy.com/site/Danby+-+Designer+11%2C000+BTU+Portable+Air+Conditioner+-+Gray/4550998.p?id=1218491581346&skuId=4550998&st=danby&cp=1&lp=1 and a PH meter.

I saw the $300 model in the post office yesterday and the exhaust hose was out the tiny window
so I walked by and felt the amount of heat being removed and was plenty impressed. For a small enclosed space
it would be great. It will remove some moisture from the air though so that may be another thing for you to consider.
The dude said he bought it at home depot. It was a little bigger than a 20 gallon trash can and the post office was
cool and it is a small cedar building with no insulation between the roof and the shingles.
I don`t like dealing with craigslist or having large things shipped so its worth it to me to just go get it along with the warranty but that`s all up to you

so in your opinion which portable AC would be the best investment?
something that wont crap out on me in a few months

I have no opinion on which to buy only what order I would buy the items you mentioned.
I`m sure someone will be able to help