Over the years I've found the following bikes:

A Schwinn beach cruiser
A Huffy beach cruiser frame, and a few weeks later, a set of rims for it
An unridden 1959 Hercules three-speed. Still had tits on the petrified tires
A Nishiki hybrid that was the most poorly maintained & hardest ridden bike ever. Should have cannibilized it for parts & thrown the rest away. Fixed it up & sold it for $120.00. Still lost muny.

My dear old dad found a Viscount & Centurion from the late 70s curbside with a sign saying "free to good home" Both are lower end models, but the Centurion sold for $180.00 after a refurb. Realy a nice little bike for the college kid that bought it. Might keep the Viscount.

You need to have patience, foresight & the ability to grab fast when something appears. The supply of decent bikes with clueless owners is drying up. Now we have crappy bikes with optimistic owners.