Why not install a factory A/C system? It is really not a huge job and you can probably find all the necessary components at the JY or on Craigslist for about $50 (maybe not incl a good compressor).
I recently picked up a complete system for something like $40.
The firewall went from looking like this:
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To this (in about 12 hours):
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The hardest part is locating the compressor mounting brackets. The normal P/S bracket is not used and there are a couple of other stiffeners etc. that must be switched.
You won't be doing it alone if you give it a shot. There are a lot of knowledgable/helpful members here who will certainly guide you through the process.