MTURK for market validation, setting the price?

I just ran a small 5 minute user feed back survey on MTURK targeting auto loans. I ran just a small sample 10 responses. I set the reward to what I thought was low, a $1 reward, about what google surveys or survey monkey would cost. It was filled within 2 minutes.

All but one response was excellent, and the info I was looking for. I guess I need a lower budget.

How have you priced MTURK surveys? It seems people are willing to do tasks for much less than expected.