Prices will certainly vary by region; however, keep in mind that boats are a luxury item and were purchased as disposable income. That being said, charge what your time is worth. What we do is charge by the foot for the hull and everything else is per job(topside, cockpit, cabin and flydecks). We also charge a premium for colored hulls.
I try to keep my hull price competitive to the marinas by charging~$2 less/ft which comes to $13.50/ft. I add $1.50/ft for colored hulls. The topside, from the rub rail up, is all by the hour. Obviously, every boat is different and not all owners want the same services. Whether they want the teak treated, carpeting shampooed or cabin even detailed all effect the price. When it comes to boats we charge $45/hr.
Without knowing the boat I tell customers to expect:$550-750 ~30' complete
$750-1100~35'+
$1100-??? ~40'+
Keep in mind that the total surface areas on boats are much greater than vehicles. Sometimes a customer will balk at our pricing;however, we stick to our guns and wait. Many times the owners do not have the time themselves, the expertise or equipment. I am also careful to point out the pricing in relation to car detailing. Many of my boat customers bring in their vehicles for complete details. These customers do not hesitate to pay $200-500 for a detail and need to be reminded that their boat is obviously much larger than their Benz.
Hope this helps and good luck