Mike Arsenault's suggestion of the Van Westendorp's Price Sensitivity Meter
Just what I needed right now (I'm struggling to find the correct price for an app, was going to go with the market).
Something that also resonates with me is:
"I wish that I knew how difficult it is to acquire a customer, get them to pay for your product and believe it’s as magical as you think it is."
Edit: changed broken Wikipedia link.
Also, I just want to mention that if you have the ability to change your price rapidly then using a dynamic pricing API might be better suited for determining the best price.
 Disclosure: this is what we do, but don't feel compelled to use us.
but at a glance it doesn't seem to work for App Store / Google Play.
Plus, I'm not sure how it would work for our intended demographic.
I'll definitely keep it in mind, looks like a great tool in the startup toolbox.