I'm trying to validate our idea by talking to potential customers. What kind of questions should we be asking in order to get objective answers?
If I were to ask: "How make xyz that helps you with abc, and it costs $x, would you buy it?"... most would just say yes, that's a great concept.
But I don't feel like the feedback is objective. How do you survey prospects when validating your idea?
You're correct - asking "would you ...yes / no" type questions rarely deliver objective results.
How to structure a proper customer development session is an art - not simply an answer.
I would suggest picking up a few books to gain some insight - Cindy Alvarez's Lean Customer development (amazon no affiliate link) is a recent entry and a good read.
Kissmetrics has an blog post with a ton of useful links as well. Best of luck!
You can rarely get an objective answer unless something valuable is at stake. One way is to ask potential users to invest in you (or your company) for building the solution. You don't need to actually take their money but their enthusiasm/excuses will give you an idea about what they really think.
Also, Steve Blank gives some good tips on how to get feedback in his books. You may want to read them.
All the best.