Late to the thread... but really important (not sure if covered before)..
You should definitely have a 1$/5$ tier to have people contribute just to contribute (no real reward).
Lots of people might just want to throw a few bucks your way without preordering (or have already preordered and want to contribute an extra dollar) or can't contribute at the 15$ level, etc...
Just saying you could be leaving a few dollars on the table ...
**edit1: sorry its been mentioned before (still relevant).
Also, rewards i would be most interested in - def name in credits and a t-shirt.
Sorry Chris, I'm sure your a nice guy and all, but if you were to come visit, id have to take you out, and I'm not sure I'm ready for that kind of commitment