I just found out, and wanted to pass this along to all Bay Area residents, the SFBAAPS
is a good organization to join as they have monthly plant swaps. Right now, there's a plan to have a group gathering/plant swap, and some visits to LFS' on July 31st. Someone has already mentioned they'll be bringing some riccia to this meet.
This might be a good starting point to obtain some good quality, and inexpensive plants.
Just a thought...