I judge the job based on how many hours I think it would take. For example, one job I did was a swirl removal on a Jeep and the client really got a deal for $100 had the Meguiars Microfiber System not been introduced.
I say had it not been introduced because the Correction Compound was the only product working for me and I managed to do the whole car in 5 hours, putting myself right at the $20 per hour which is the lowest I like to stand on correction jobs.
But, the most important item here is to think of your expenses and how much you need to make. For me, $20-$25 per hour on correction details works while for you, maybe more is needed. I know that if I had to take care of a shop also then I may have to bump up the prices but right now, part timee and only in the summer, $20-$25 works for me.