Update:

I looked all over and didn't find a smaller pulley that would fit.

However, I got in touch with the company that I bought my alternator from, here:
http://www.qualitypowerauto.com/item_342/Kia-Sportage.htm

It turns out I'm in luck. They sell a 140 Amp alternator for our Sportages. They just recently started also selling a 200 Amp alternator for them (it's so new it's not even on their website yet). For the 200 Amp alternator, they have a smaller (1.8") pulley custom-machined just for our vehicles. The catch is you have to remove a little lip from the alternator chassis to make it fit.

So, for $40 they sold me the pulley, and I will remove the front of my alternator case, grind off the lip, and install the smaller pulley. That should spin the alternator a bit faster and let me maintain a solid 14v at idle even with my electric fan on fully blast!
<img src="/forums/images/graemlins/kewl.gif" alt="" />

I highly recommend these guys for anyone looking for a high-output alternator, but I'd buy the 200 Amp model now that they are selling it! You'd need to call them to order it, I guess, because it's NOT listed on their website / online store yet <img src="/forums/images/graemlins/notooth.gif" alt="" />

I guess $40 probably sounds expensive for a pulley, but IMO it's not, when you consider that they had to have them custom-machined out of billet aluminum for this vehicle. There is no mass-produced overdrive pulley that will fit this vehicle's stock alternator. If I was starting over buying a high-output alternator I'd order the 200Amp model from these guys because it's a drop-in replacement, no custom work needed. But that might be less fun for some people <img src="/forums/images/graemlins/wink.gif" alt="" />