Eastbay- If you leave from DL or the larger hotels, the express bus and the popular shuttle services charge $15. Since there's a lot of volume and competition the fares stay low; going to LAX from a point just a few miles away can be $40-$60. One thing is they may spend time picking up passengers at other area hotels as you state, but once you're under way I'd expect a straight shot to LAX.

Whether you leave from Irvine or DL, try Karmel Shuttle. I've been happy with them over the years and never seen a complaint on any of several travel forums I lurk. Prime Time is reasonably good but I've read a fair number of complaints about Super Shuttle.

Another option is Metrolink or Amtrak from Irvine to LA Union Station, then the Flyaway bus to LAX. Or, rent a car...Enterprise is pretty reasonable and has convenient locations in the Irvine area. Check their policy and fees to drop off at LAX....one quirk about Enterprise is some locations don't allow ow dropoffs.