Thanks for your quick reply. We make our cruise with 3 adults and when we book with our cruise agency we have to pay $100 each to get from Mexico to San Diego. We assumed that we were able to travel for less then $300 if we managed to find our own way towards San Diego.
Our airplane only leaves the day after, so we're not in a hurry to get to the airport and we can go to our hotel by shuttle from the airport, so that's not the problem.
Good luck. I have not heard of anybody going to Ensenada other than to board a cruise ship. The route from Ensenada to San Diego is not exactly the beaten path for commercial transportation. The quoted price of $100 per person sounds very expensive for the cruise line's transfer service. I would expect to pay no more than half of that price.
You might also want to consider that the crossings along the Mexican border are the subject of an ongoing crackdow due to illegal immigration. The cruise ine's transfers probably will not be the subject of immigration officers' concers at the checkpoint, whereas some other vehicle might draw a lot closer scrutiny at the border.
JTOL, your best bet might be to book your hotel through the cruise line. The quoted price may sound a bit steep, but the cruise lines generally use the better hotels and include the transfers in the package.