I recently went on a solo ride to San Rafael, and checked out the Re-Cyclery Bike Thrift Shop (and fundraiser for Trips For Kids) while I was there. Quite a place.
Outside, a classic Schwinn (for sale for $125):
The back patio had many more used bikes, in both adult sizes and kids’:
There were many other sub-$150 used bikes:
Indoors:
Used cranks, cogs, wheels of many types and sizes:
Clipless pedals, typically $20ish for a basic SPD pedal set:
They also had an area with used reflectors, lights, computers, seat bags, and other accessories (I picked up an old water bottle with a design I liked and colors that matched my road bike, for a dollar).