Another option is coronaSDK, just an alternative to cocos. I've used it a bit, very basic python script, big community and tutorials/examples. Full licence is $350, indie is $200. http://www.coronalabs.com/products/corona-sdk/
Looking cool so far - I agree with danpaz3d on the silhouette, though. Regarding 2d engines, I personally wouldn't recommend torque2d - I found it to be laggy on the iPhone. To be fair, that was an older version, so maybe it's been improved... If you're comfortable programming in Obj-C, I'd go with Cocos2d . It's not…