I haven't heard of a solution that you're looking for. What you could do, however, is a couple of different things. Throw up a survey on your site that describes the product and asks for feedback on pricing, suggestions for features, etc. A GREAT site for this is Wufoo - HTML Form Builder - Free Contact Forms & Online Surveys ; they have a free trial version.
If you really wanted to get complicated you could setup numerous landing pages that are identical except for price and see the differences in signups, and just use google's analytics tools to do an a/b testing of sorts by serving up a different landing page.