Having tried to book cash + upgrade from WT+ to CW to SAN over the last few weeks for next Christmas without success, I thought I would try by booking one way at a time. I've now got flights back (from LAX) in AA Business using Avios. BUT! when I tried to book one way from LHR to SAN for cash in WT+ the price has shot up from £609 to £1883. A return is, er, £1218 so am I stupid (entirely possible) or is it a glitch or what?

Help most gratefully received...