Proportion of revenue is a bad measure for this reason - costs don't scale proportionally. The rent, food and utilities you're siphoning out of that 100k along

Proportion of revenue is a bad measure for this reason - costs don't scale proportionally. The rent, food and utilities you're siphoning out of that 100k along with all the incidental costs on top of it don't really apply evenly as revenue increases. As someone making right around 100k I'd say that 500$ is a big enough penalty that I'll notice it but if it was a one-off (like this one was) then I'll shrug and eat it. For instance if I were getting my bathroom remodeled and wanted to install some nifty european shower head that's against code... I'd probably be alright with the 500$ surcharge.