If you're going to take the air conditioning route, Something you might consider (depending on the size of your collection) is retrofitting a makeshift growing 'case' with a thermoelectric cooling air conditioner you find in some miniature fridges. You can find one on ebay, just search thermoelectric air conditioner. 400 BTU units will be more than enough for a well-sized space (I forgot the exact measurements, you can find a converter online to translate BTU into sq. ft.) make sure its in a 'well' insulated case, but I wouldn't think you'd have to get too crazy. It would have to be custom, as the cooling element side would have to be facing inward, and the hot side outward.
This is assuming you have the money (I think thermoelectric air conditoning units run a couple hundred dollars), time and patience to create such a space LOL! Just suggesting, as I went the air conditioning route and now regret that I spent all that money just to find out I needed something smaller... like the thermoelectric air conditioner.