how much should it cost for a dealer to ship a car?

That’s not how sales and use taxes work (generally–each state has its own laws, but generally they all work the same way). Generally you don’t have to pay use tax in a state if you paid sales tax on the purchase of the item in another state. So, the relevant consideration is the sales/use tax rate in the two states.

Dealers usually get better rates in the auto shipping industry as they have connections with the actual trucking companies. If you are not sure if he is trying to ‘pad’ in some extra costs, you should get some quotes from auto transport companies to make sure his price is within reason and not more then what other auto transport companies are charging.
auto shipping

Yeah, this is wrong. I’ve done this numerous times. You fly in, you complete the sale, you call your insurance company and add the car (or use their website), you drive back. Once in your home state, you register the car and pay taxes.

If you’re buying a new car, the dealer takes car of those shenanigans; mine even called the insurance company.

I usually shoot for a weekend, but I’ve done epic road trips where I flew out, drove all night and went to work the next morning.

Well good luck flying into California and driving it home without paying tax and registration.
If we sell a car and load it on a transport no tax no reg. you drive it you pay period.
But hey I just work at a dealer, what do I know.

That appears to be a weirdo California rule. In most, if not all 49, other states there is zero problem buying a car in another state, driving it home on a temporary plate, and paying all the taxes and fees on it in your home state. There’s some dealers where almost all of their business is out of state “fly and drive” deals like this.

I’m on the east coast.If you’re interested in saving $100, I’ll pick it up and drive it to you for $900.

Shhh, don’t tell him we don’t do California Emissions everywhere either.