This time last year, Amazon.com Inc. (NASDAQ: AMZN) was on the verge of selecting Arlington County for part of its second headquarters. Buyers wanted homes in Crystal City, but there weren't many for sale.
Fast forward to today — little has changed. The few homes that hit the market often sell well above asking.
The median home price in the 22202 ZIP code, which encompasses all of HQ2, was $815,000 in October. That's about a 51% year-to-date increase or a $275,000 difference, according to data…