That is just insane.
Half Life 2 is a steal at less than six quid.
Episode one is a steal at less than six quid.
Episode two is a steal at less than six quid.
Team Fortress 2 is a steal at less than six quid. (The PC version is easily the best version, and it will run on pretty much anything.
Portal is a steal at less than six quid.
As a package? You would be mad not to. If I didnt already have this on the 360 and the PC then I would snap this up in a heartbeat.