if it's only 3k installed (which sounds low) i'd get it, sellyour old ac's, and put it otwrds it.
my thoughts are that, at that price (again it sounds low), it's worth it come resale, if that time ever comes. it'll be cheaper to run than thother three too, may never "make your money back", but you'll see some payback. that and the resale make it worth it, i think.
i'm not a dyed in thw ool mustachian yet, though, so take it for what it's worth