Air conditioning considerations

Now that the fake Seattle summer is here, and the real is not that far away, I'm thinking of getting an AC. The only problem is that the 'single duct' air conditioning that's so often sold online and offline for a few hundred bucks is actually quite crap, and the dual duct machines -- ones actually working -- are hella expensive. Conversion from single to dual appears to be possible, but perhaps beyond the scope of my knowledge and skills.

I don't know how to align my differing and competing needs: the pricey dual duct AC's have unclear value...do I really really need that much of appliance that'll be thrown away in a year or two? Can I just go to the library and to the office instead, and work there when it's hot?

The one reason to actually consider getting one is so that friends won't be sweltering in the middle of the summer and will be willing to get into the oven of my apartment, but then...how many are coming to hang out anyways and if it's like 10x, would that money be better spent on otherwise spending on entertaining in their company?

Some serious tradeoffs and give-take considerations are being taken into account, what a crazy competitive issue I have found myself in.