I only did something similar, it's not like I can go around handing out cash! What I did was ask two questions. The first: "Have you heard of bitcoin?". (It was a while back, bitcoin had a price of $400-$600) Most people answered "No", but it often led to some discussion of what it is etc.
The second was a hypothetical question: "Right now 1 bitcoin is valued at $400. If you were given the choice between 1 BTC or $400 which one would you choose?". Almost all chose $.
Interesting enough it felt as though people would choose bitcoin if it was valued less. For example choosing between $10 or 1 BTC they might as well choose bitcoin because $10 isn't worth much to them anyway.
Maybe it's a good way of measuring the real world value of bitcoin and not the speculative value that is at the moment.