Money
Are they willing to pull out their wallet and pay for it? for B2B, are they willing to sign a non-binding letter of intent to buy?
Reputation
Are they willing to put their reputation on the line by recommending it to their friends/co-workers/boss. Would they share this on social media? Right now?
Time
Are they willing to "donate" their time to work with you on this feature/product?
Account access
Are they willing to provide login credentials for their current solution (or some online service) to gain access to our product/feature ? We don't actually need it - we are just trying to assess how much they value our proposal