Now this is some seriously good thinking. Did not cross my mind about a window ac which is way more efficient than portables.

http://woodbox.dparker.org/

Ramming 18 C cold air straight down SP10 throat 

MSRP 109 $ probably find it on sale a lot less

http://www.lg.com/us/air-conditioners/lg-LW5012J-window-air-conditioner

500 watts
52 dB (which is emitted out the front end)

Find an even smaller unit. Less btu, less watt, lower dB, less price.

10 $ of scrap wood of if you hover around the lumber section of home depot, and ask nicely 0 $

Make the box as big as need for as many machines you have. Go so far as to insulate the interior with soundproofing foam for added measure.

Very interesting. Stick it on your balcony, patio, in your basement, in your garage and you're set.