A survey revealed at the MI6 Games Marketing Conference gives us some interesting figures regarding the purchasing habits of gamers. Apparently, if you own an iPhone you are something of a cash cow. From Gamespot.
Perhaps more importantly, iPhone users also buy more games for any platform. The average number of new games purchased in the last 12 months by iPhone owners was 4.57--more than all other systems. Owners of Sony's PSP were the second most spendthrift gamers, picking up an average of 4.12 games each during the previous year. The PlayStation 3 was next on the list (3.99), followed by Palm PDA owners (3.70), the Xbox 360 (3.55), the Wii (3.44), and the DS (3.39).
The results for used-game purchases were slightly different, with PSP owners topping the list, reporting an average of 2.71 used games bought for any platform over the past year. That was followed by the PS3 (2.54), iPhone (2.33), Xbox 360 (2.15), and DS and Palm PDAs (2.01 each).
These are the same people who overpay for a CELLPHONE THAT SUCKS AT TEXT. Hey, it's great that it works as a level, and has games, but 95% of what I use the far superior Blackberry for is as a PHONE and to EMAIL / TEXT MESSAGE.
The IPhone keyboard is utterly useless.
The IPhone users are a dream market for selling anything shiny and new, so long as it's utterly vapid. This is the Wii of the handheld set.
I'd say average purchase price of the games, and overall number of games sold, are far more important than the platform customer-attach-rate. Cost of development would be more important as well, as would several other factors I can think of.