The reason why auto transportation services are so expensive is because it costs a lot of money to operate a huge ten-car carrier and haul a bunch of cars across the country.
How much do you think you would spend if you were to drive your car across the country? In gas alone you're looking at $600, if your car gets 25 miles to the gallon with a 15 gallon tank averaging 12 hours of driving at 60 miles per hour. Now factor in lodging and rest times and the oil change before you go and after you go and the tire replacement and pretty soon you're dropping $1500 or more to drive your car from California to New York. That's a lot - and a lot more than what you would pay with auto transport.
Auto transporters can transport up to ten cars at a time and they pick up and deliver other cars along the way. They're cheaper because they actually get paid to do this, and their expenses are covered by the money you pay them. And while it may be expensive, it won't be as much as the $1,500 you would pay to drive your car yourself from California to New York.