From 1913 to 2014, $0.02 cents inflated to $0.48 cents. At that rate, wouldn't it be over 100 years before reaching $10? In which case, in 2014 he'd have to share 20.83 opinions per session to justify the cost.
I tried to find a year for which $0.02 in today's money today would be approximately $10, but it turned out that you'd have to start somewhere in the middle ages, and the error bars get pretty large.
That's inflation adjusted, but now you need to do the compound interest to get it from $0.02 to $10.