I am amazed at the amount of trivial mac apps that sell for $20+. OMG, bold font pro and spellcheck+ are on special offer! Culture shock for a Linux user.
This is true, but there are quite a few high quality applications that that kind of culture enables as well. I would gladly pay for an ftp app as nice and polished as Transmit 4 on Linux, but as far as I know one doesn't exist. Not that there isn't great software on Linux, but I enjoy the emphasis placed on design by the Mac community when it comes to the top applications.
Not that I have any data to back that up, just my general impression.