I just booked my flight to Santa Barbara and there is an Amtrak train that travels between Santa Barbara and Oxnard. I was able to get a round trip ticket for $23.50. The train station in Santa Barbara is near the airport. In Oxnard it looks like it is a taxi ride to the hotel.

I considered flying into LAX since that was cheaper but it costs $14.00 round trip for the LAX Flyway bus to Union Station. Amtrak from Union Station to Oxnard is around $38 so compare these prices with shuttle service offerings. Don't forget to factor in the hassle factor when deciding on your best option. Saving a few bucks but transferring a lot should be compared to the convenience of door to door service.