Maybe you could do something similar to Google Fi's pricing model for data usage. You pick a monthly amount of data, say 2GB, for a monthly price of $40. Any GB you use in excess of that is $10 per GB up to a maximum of $80, and data usage is unlimited after that.

I would bet that my usage most months would not exceed $5, and I think many other prospective users would be willing to gamble on that as well. Food for thought.