I have a basement Home Theater that's kept reasonably cool for the most part (even during the peak summer months), and I use a portable dehumdifier to keep the relative humidity in the 40-50% range. The house's upper 2 floors have central air conditioning/ducts already, but unfortunately the previous owners did not run any of its ductwork to the basement (which I understand is typical in 1970's homes like mine that have only semi-finished basements). I finished my home theater last year, so the basement is now half-finished (theater side) with mechanical/boiler/workbench on other side. The central air A/C unit itself is just outside of the unfinished half of the basement, and all coolant lines etc. go up the side of the house 3 floors to the attic, to the air handler/distribution.

The home theater came out great, but there are few occasions where I would just like to spot-cool the theater and lower the humidity even further (especially on those really hot/humid days when guests are over in the summer).

What I would like to do is find the best, most cost-effective solution, whether it's somehow running additional ductwork into the basement, using a 'portable' air conditioner, or even a 'swamp cooler' if that might make sense. The discomfort felt in the home theater is compounded when more than perhaps 3 people are in there, exhaling their collective CO2 on those really warm and muggy days here in the Boston area.

The space (theater) to be cooled and dehumidified is only about a 12'w x 18'd x 7'h space. This is not a 'wet' basement; very little moisture down there overall.

This solution would only be used when several guests are in the theater, and when it's pretty darn hot, so its use would be infrequent. Ideally that space would have its own separate zone for cooling, regardless of the solution (added ductwork for existing central a/c system, or a portable unit). Another factor would be the noise generated----ac's are of course fairly loud where a theater is concerned, so the quieter the better!

I've heard of Mitsubishi's Mr. Slim unit (MS09TW, specifically, at 8,000 btu should suffice nicely for my space), but all-told (after I received a quote for electrical and plumbing involved to install the thing) it came to about $3k! Ideally, I'd find some solution one way or another within my $1,000 budget.

Thank you and I look forward to any responses!