Ask HN: How much should startups pay per beta tester?

For startups that pay for usability testing and feedback what is an appropriate price to pay? I know sites like UserTesting.com charge about $40 per test. It inspired me to create a campaign to try and gather some data about what startups would be willing to pay to use a service like "UserTesting" to get feedback for their site / concept / design etc.

Visit http://takemymoneys.com/usertesting to participate in the pricing campaign. Hopefully we will collect some interesting data.