I'm absolutely OK with $20 for 6 hours of fun (and even replay-value due to achievements etc.) I mean hey, I pay $17 for an average blu ray with an average of 2 hours of run-time.
Also, i paid about $40 for Mirror's edge and didn't regret it because it was awesome 6 hours of great gameplay. It was even a bit too long in my opinion.
I prefer having a short but intense and varying experience than a repetitive game.
Just look at Clive barker's jerico, for example. it's a 5 hour game stretched to 15 hours by copypasting enemy spawn scripts :>
So yeah. if you're just looking for a good gameplay time/price ratio, tell me and i'll program you a text adventure with a "there's a huge boss monster in front of you. what do you want to do? (attack/die)" and you have to type "attack" a million times because the monster has ten million HP and you do 10 damage
i'll sell you the game for $1 then. The ratio is better than the ratio of the ball!
But if you just want a great experience, get the ball as it is (or will be) and see what i'm talking about.
i'd even pay $40 if I had a choice
Hey, how about a collector's edition with a miniature of the ball?
i know, it's a bit late for that.