Why would you showcase your theme with a font that you cannot include due to price? Not only is it not free, its a huge price.
Its kinda like sayin' FREE IPOD! then once you get in the store, they tell you that you have to buy a $2000 iMac to get it. Sure you have a small note saying its not included, but half the screenshot involves the font. Oi.
The font he has in the screenshot complements the theme very well. I'm sure you could find a font similar to the one in the screenshot. Then just change the system font. That's what I did anyway.