If you're doing this as a weekend detailer then charge what you can get cause you're doing it, I would guess, as a hobby so working 5 or 6 hours for $150 is just some extra spending cash eh?
Now if you're doing this for a profession then you won't survive long at those prices. You need to make at a minimum $50 an hour. You need to factor in cost of materials, tools, insurance. Gas if you're mobile, rent if you have a space, etc.
We charge $60 to $70 for a 4 door sedan to wash, vacuum, windows, wheels, tires. More for trucks. If it's a regular client we will spray wax with each wash at no extra cost.
Interior detail starts at $95.....and that's for a pretty clean car. Typical interior detail, steam and extract, door panels, dash is $150.00
For your description of the van I would say more like $200 to $250