What iOS device to use/purchase for testing.

What iOS device should I purchase to do proper iOS testing? An iPad is out of the question. I am thinking about a 3rd gen iPod Touch with 32GB of space. Should I go ahead and get a 4th gen iTouch instead? Also, I plan to purchase a mac mini to create the game on - any idea what the minimum requirements are for Unity to run on a Mac mini?

Unity has a system requirements page.

As for what generation iPod you’re going to get, consider this: the computing power differs significantly between generations. I’d say pick up the oldest model you intend your game to work on, or just write off older generations of the devices and get the latest thing.

Get a 3rd gen and a 4th gen touch. They are very different, and it’s quite possible to make something which runs well on one but not the other. (And it’s not a given that the 4th gen is always faster; the resolution is 4X the 3rd gen but the graphics chip is the same.)