Cost effective server room air conditioning?

at0mic26 writes: "I am currently tasked with finding a cost effective solution to our 30+ degree celcius server room. The only air conditioning currently provided is a single duct pipe from one of two air conditioner units. I was thinking of stealing air from the second air conditioning unit with some sheet metal work but it likely will not be sufficient and would not have tolerance to both AC units being offline for any amount of time. An ideal supplimental portable AC unit is what i am after however im finding it cost prohibitive with $600+ humidity controlled AC unit, plus 20 amp socket requirement, plus contract work to make a hole in the wall for outside drainage so that the unit does not flood the place. What sort of sucessful cheaper air coniditoning solutions have you come up with?"