Fueled Insights, a market research firm, recently published a report that helps races understand why they need to differentiate their race. The report is available (and highly recommended!) as a PDF below:
Fueled Insights – The Fight for Runners’ Recreational Dollar
One of the analyses they dive into is the rising price of races:

The report also provides further insight into what activities runners choose to do and even why runners choose not to do a race:

There are a number of very good insights for every race director in this report and well worth spending the time to read.