Bart to Caltrain to the VTA shuttle is the current best way, as others have noted, but you do need to check the new Caltrain schedules (have they appeared?) to see if the trains will still be running when you need them.

I bet a shuttle from SF to SJC will be at least $50, but I've certainly been wrong before. If you consider the shuttle route, it might be a bit cheaper to use Bart to SFO and shuttle from there. Then again, it might not!

Beware of long waits in shuttles, as they often won't go for many minutes if they aren't full.