We used a great van service recently: Harold's Transportation Service (www.haroldsmulti-passengervanservice.com). It's based in Orange county and serves the southern CA area. The van seats 10; round trip DL to LA was $65., plus tip. The driver was also wonderfully informative.
An earlier post recommended Primetime Shuttle, with rates based either on the number of passengers or on the whole van (www.primetimeshuttle.com).