Haha, thanks, I guess that's one place where Dependabot shows its side-project roots - I just want as many people to use it as possible, and am less fussed about capturing the biggest share of value.

You can still get that benefit with the lower tier. I would definitely raise the prices for your higher tiers, because those are going to be for businesses, and they have money to spare. You might see your ARPU go up considerably. :)