The short answer is, you don’t. Pricing is an emotion-laden topic and when confronted face to face, most people won’t give a straight answer. You will get bad data if you attempt to ask someone face to face, “How much would you pay for this?”
Instead, read Elaine Chen’s “A primer on primary market research” on Slideshare – look up the section on quantitative research, in particular check out the monadic, multiple monadic and Van Westerndrop techniques. Those are some common ways you can do pricing research.
Now, pricing research gets you data but it will not get the behavioral validation you need. The ultimate pricing research is when you offer your product or service to a potential economic buyer and attempt to close a deal. Offering a pilot in a B2B setting or a pre-order in a B2C or B2B setting and having actual customers send you money or issue a purchase order is the ultimate experiment in pricing research.