cheap a/c

its gonna transport all that heat it sucks out of one room to the other room you are using for the "outside". It really needs to be in a window, but you can try it like you say. My bet is its gonna get real warm in the bathroom. To answer your question, yes it only has to get air thats not coming from the room it is cooling. I would think the smallest 110 window unit you can find would be enough. They make what is called a "portable" air conditioner that has an exhaust hose on it that might be easier for you to use, of course they cost a little more. like these: http://www.homedepot.com/Appliances-Heating-Cooling-Air-Quality-Air-Conditioners-Portable-Air-Conditioners/h_d1/N-5yc1vZbv64/h_d2/Navigation?catalogId=10053&langId=-1&storeId=10051 Maybe you could vent it to the attic?

It needs a fresh air intake.

yes after like 3 hours of reading posts and your suggestion i think im going to just buy a portable and vent it out to the attic,thanks for the input though,

Have you tried just forcing air from outside the grow room in there with just a small fan to see if that helps or leave the door open maybe? I know it doesnt take much to drop my temps a little, just a fan blowing. Here's a thought, maybe you could just put an exhaust fan in the ceiling in the closet and let it suck in fresh air from under the door through the room, like one of these:
http://www.lowes.com/pd_207236-14-S97014094_0__?productId=1233431&Ntt=exhaust+fan&Ns=p_product_price|0&pl=1&currentURL=/pl__0__s?Ntt=exhaust+fan&Ns=p_product_price|0&facetInfo=

pretty cheap actually