Sounds like a great use of Amazon Turk. Ask people tiny questions as they proceed through the workflow before purchase, without requiring purchase. Conclude with, “if you did have a spare $x.xx in your bank account, why would you NOT be inclined to spend it here? Say ‘I would’ if you would, instead.”
I would balance Amazon Turk with some people on Fiverr who would be willing to judge the site workflow and give you their opinion.
As for tracking, you could use the action tracking in the free version of Piwik pixel tracker to track events in real time. Combine it with the traffic IDs passed in via Google AdWords or Facebook, and you then get some great data to see where people drop off.