This is not a sure bet, but just ask about their latest funding round and how much they got and how much of a percentage they gave to the investors. For example

This is not a sure bet, but just ask about their latest funding round and how much they got and how much of a percentage they gave to the investors. For example, Company X just closed a 1 million dollar Series A and gave up 50% equity. That means the company is valuated @ $2 million.