@picus - I thought I was the only one that hated interiors 
I price out hourly on the low end because I am just getting started @ $20/hr with a minimum charge for 2 hours. This assures me of getting $40 no matter what.
The only variable in my pricing is like someone mentioned above how much paint correction do I need to do on this thing, when that is established w/ # of hours needed its cake from there. Tires/wheels/wells ALWAYS get cleaned and dressed, no exceptions because lets face it lots of people the first thing they see is in this order:
1. better looking paint (shiny)
1.5 cleaner wheels/tires
2. dressed tires
I also dont do ala-carte pricing, its all hourly for me. If a customer requests me just to clean the tires/wheels/, then hey I have a jack and some jack stands, no problem I jack the side of the car up and take the wheels off and go to down on the front and back sides and they get charged $20/hr with a minimum of $40 to start, I even seal the front and back sides of the wheels.

I price out hourly on the low end because I am just getting started @ $20/hr with a minimum charge for 2 hours. This assures me of getting $40 no matter what.
The only variable in my pricing is like someone mentioned above how much paint correction do I need to do on this thing, when that is established w/ # of hours needed its cake from there. Tires/wheels/wells ALWAYS get cleaned and dressed, no exceptions because lets face it lots of people the first thing they see is in this order:
1. better looking paint (shiny)
1.5 cleaner wheels/tires
2. dressed tires
I also dont do ala-carte pricing, its all hourly for me. If a customer requests me just to clean the tires/wheels/, then hey I have a jack and some jack stands, no problem I jack the side of the car up and take the wheels off and go to down on the front and back sides and they get charged $20/hr with a minimum of $40 to start, I even seal the front and back sides of the wheels.