A friend and I want to try making an iPhone game, but we don't really have a budget to speak of. From what I've found, I need the iOS SDK, and that costs money. Is there really no way to make an iPhone game on a $0 budget? If not, can I do so for the Android?
The Airplay SDK: http://www.airplaysdk.com/ as well as some other other mobile SDKs, will let you make iOS games for free (in the sense that you don't have to buy a Mac), but I believe it will still cost $100 to get your game on the app store, no matter what tool you use.
The Android is free to develop for and deploy to (Edit: per the comment by Ricket, it's actually $25 to publish on the app store). You can also make an HTML5 web game, and people with iPhones can play it in their browser, at no cost to you (or them).
None of the other answers addressed a basic misconception in your question: the iOS SDK does not cost any money. You can download Apple's developer tools for free. However you will only be able to test in the simulator for free; in order to deploy onto device you need to purchase the $99/year developer registration.
The fee is for the ability to publish, not for the SDK. Subtle but important distinction.
So no, there is no way to make an iPhone game without paying a fee. Android does not have any fee to deploy to device, but the individual marketplaces have their own policies.
If you want to publish or test it then no. The minimum you can spend to publish a game is the yearly $99 fee that you are talking about for the SDK. Apple simply won't let you post a game to the app store if you aren't paying to be a developer.
If you want to make one and maybe publish it later, find a game engine like Unity3d that will let you make it for other platforms and easily port it to iphone when you're ready. That's the route my team took a few years ago when we were just starting. We made our game for Unity's browser plugin then ported it over to IOS when we bought the license.
EDIT: FYI, unity and a few other engines are completely free just for this purpose. Once you want to publish to iPhone though you will need to also buy the unity IOS basic license at minimum which is $400, but if you have a game worth anything you may find somebody willing to pay for your licenses for a percent of the game.