There are dozens of threads about the same thing with all the online ticket places. They don't check real time availability when they price out a ticket. It's when you click through to buy the ticket they actually go and see if there are any seats available at that price or not, and in your case, it's not.
Now they will all tell you that prices are changing all the time and it must have happened while you were on the site, but as you found out you can repeat it for days or weeks.
So no, they are not playing games, it's just how their system works.
It happens on Kayak too
http://www.flyertalk.com/forum/onlin...lly-exist.html
and Delta
http://www.flyertalk.com/forum/delta...card-info.html
and so on.