Wow! I'm surprised that they're already sold out at your Best Buy store. But if it's the only one within 50 miles, maybe that's where everybody goes to buy their Kindles!

You can also buy a Kindle at Target and Staples. Is there one of those that's closer to your town?
I just checked, and Amazon.com still shows the Kindle as "in stock" (for both models -- WiFi-only and the 3G + WiFi version). Earlier this month the 3G version was listed with a warning that it would ship "in 8 to 9 days," but today they seem to have plenty of Kindles. So in a pinch, you could always try ordering your Kindle online. For a little extra money, Amazon will even deliver it overnight...