As you may have noticed, there are several titles available on the PSN in the form of the new PSP Minis. These PSP Minis are also on the App Store for Apple’s iPhone and iPod Touch. Many have complained that some of the Minis are too high in price compared to the App Store counterparts. One glaring reason behind the price difference is the necessity of having an ESRB rating on the Mini titles.
Sony doesn’t allow a game to grace their console(s) without an ESRB rating, and there is no way around this. If there is no rating, the game will not appear on any Sony console.
Sergei Gourski, the developer of Fieldrunners, had this to say:
“You have to invest some money into dev kits and into getting ratings for your game. The costs of ratings such as ESRB is significantly more then we had realized”
The estimated cost of the ESRB rating alone is around $2,500. Since games on the App Store do not require an ESRB rating, they get away with a much cheaper asking price.
[Source]