CPC dropped from $20 to $0.01 from google Adwords

I was building my first website aiming for a keyword that had a cpc of $20 with low traffic.

And I just checked Adwords and the CPC dropped to $0.01 in one day.

What should I do? Can this happen? Was it a bug?

You could run your own adverts at $20 a click so your CPC goes up........