How many iPhones/iPod Touches have been sold? How many iPads? So if a developer wants to get the same return for the iPad version as the iPhone/iPod Touch version then they have to charge far, far more. It's the penalty of a less popular platform.
But but but..............
It's not the same is it.
You have to think up a game, perhaps storyboard it, or at least work out what's doing to be going on.
Work out then start writing all the logic/the code/the maths etc etc.
The actual core, the guts of the game engine.
You release it for 99c on the iPhone.
Then you wish to do an iPad version. You don't have to do all that again.
Of course, there may be some graphics scaling up (not much from Retina, if any for much of what's on screen) and of course, the location of buttons, and perhaps a little behind the scenes stuff.
But that's nothing at all like the amount of work needed to create the item in the 1st place.
99c and 2.99 is ripping iPad people off without question.
Perhaps the iPhone price is too low?
But there should not be such a mark up when 80% of the code it probably the same.
If it was a totally from the ground up re-write then I'd accept it.