Good point @Thedamnthing but hours/revenue would be hard to calculate as it's all down to how well your model sells. Someone like Stonemason doesn't produce much but I imagine he sells very well, while others produce a lot (arguably lower quality) at lower prices. A newer PA would likely spend more time on a model and a more experienced one relatively less as they have more experience, an established workflow and can "recycle" textures etc. That said, I'm pretty sure nobody selling Daz/Poser content does so as their main source on income.