To me, $4.99 seems as arbitrary as $0.99, and if you want to avoid being accused of under valuing it then pricing it at say $99 (the price of the developer programmes) might be a better bet as it would make the dev programmes a no brainer and nobody could accuse it of being undervalued.

I'm still sitting firmly in the "not convinced" camp!

It's irrelevant to me anyway as I have paid for the iOS developer programme.