well waldo, two things my advice is not... Good, and cheap!!!
Michael, keeping the above in mind, i'll comment anyway.... do you plan on storing wine in there over next summer?? if its 80 degrees now, it will probably cool down soon, so maybe you can get by now, or wait a couple weeks... but if you plan on storing wine in there over the summer months, it might push above 80 degrees and then you're in trouble... 80 is not good for storing/aging anyway... if you are, you might want to look into a portable AC ubit or some kind of refridgeration unit for the closet (would need doors).... there is a great book on winecellars at Barnes&Nobles in the wine&spirits section that might help give you some ideas