I think what certain people do is just use other industry's/software prices as a yardstick and then claim the prices are too low by comparison.

But that's a brainless argument. If you are catering to a different income group or customer type, or a much bigger community where you have more sales volume, and you don't have to pay WordPress a license fee to develop plugins, then there is no reason why your costs should be the same, they should be less.