I have released a few apps in the app store but wanted to take a new approach. I feel like it takes time to perfect an app especially games. From a business stand view, it has not paid off all that well. I figured rather than spending the time and money starting from scratch, why not just spend the money and buy something that has been done and polish it. With that said, I am looking to see if anyone has a game/app that would be willing to sell it's core functions. I am not looking for a complete app, I just want to take what you have done and make changes to it. For example, you have a tower defense game. I would buy the core functions of the game but will completely change the graphics, add or take away certain features, make different levels. I feel like the hardest part is creating those initial stages. If you are interested, please message me with info on your game/app and a link to it if it's in the app store.
I don't know if this is what you're looking for, but the lead programmer for the Cocos2D projects sells the source to a game he wrote: http://www.sapusmedia.com/sources/ I haven't purchased the source myself, but if you do buy it, the money you pay goes toward the development of Cocos2D, which is a great 2D engine for iPhone.
Unity 3d I guess Unity3d is out of the question? If I were in your position I would approach developers that have built a game you're interested in and give them an offer. As long as it's a good price, why would they refuse? The key word though is "good". Think about how much you're willing to spend and go for it.
Offer? Let me rephrase my post. Is there anyone that has a game that they would be willing to sell me? Is so, message me the name of the game and we can go from there.