You guys are probably already familiar with this link, but I thought it might be useful in determining where/how to sweeten up the right reward tiers:
http://www.kickstarter.com/blog/trends-in-pricing-and-duration
In short, Kickstarter did a study of all of their projects at the time and broke down how much a reward tier generally provides to the overall income of a project. Generally, they have found that 100$ and 50$ tiers contribute a higher percentage to the overall project funding than any others, so it might be worth your time to see if you can expand the value of those tiers. Of course, I understand that expanding the value of a 50$ contribution might not have a whole lot of legroom while still maintaining profit, but it's still some very good info to have.