Personally, I'm willing to pay (a little) more than $10 for a new game, but it depends. I think $12 for a completely new release like Grimrock is awesome, as for Trine, most people probably already got it for less, but $10 is still a fair price, The Whispered World for $15 might be a little overpriced by now, especially considering the lack of multi-language support (you can get the original retail for less), but not by much. Anything up to $15 is still a fair price for a decent game with several hours of gameplay in my book, even or sometimes particularly if it's an indie game.
This price range for this particular kind of product... been available and cheaper elsewhere, sets a 'dangerous' precedent as to what we think is acceptable and not acceptable.
And in all honesty.. $14.99 for this simply isn't worth it.