Very good points here. The prevailing advice for entrepreneurs from folks like Steve Blank is that you must "get out of the building" and be physically in front of customers to interview them, but in my experience 95% of customers would never tell an entrepreneur their product/idea sucks right to their face.
As for pricing, I've found that asking people "What do you think a fair and reasonable price for X would be?," followed by the follow-up as to why, is the best way to ask about pricing (in a qualitative setting, at least).
I think Blank is entirely right. But you have to be tricky.
At my last company we did user test every Tuesday afternoon. When seeking subjects, we looked like a research firm, not a product company. When they arrived, there was no company name on the door. The interviewer would start out asking about a variety of products to get a baseline; ours would just be one of several discussed. Eventually, because we spent more time on our stuff, maybe half the people figured out that one product was ours, but by then we generally had enough honest opinion.
As for pricing, I've found that asking people "What do you think a fair and reasonable price for X would be?," followed by the follow-up as to why, is the best way to ask about pricing (in a qualitative setting, at least).