Try thrift stores eg Goodwill at South Van Ness & Mission Street in San Francisco, probably $50 or so. Call them up, ask for the computer department.http://sfgoodwill.org/store-locations/
LOL! The computer department! You mean the department for stuff besides clothes.
Boaty, you could also just walk in and ask them if they have a computer monitor, and that it doesn't even have to work.
I know working at one of the Goodwills, here in Denver we got all sorts of broken computer stuff. The folks dropping it off would say "I bet you can get it fixed for cheap. Then sell it and make money."
Yeah right! Like Goodwill sends anything out to be fixed. People didn't know that we had giant watermelon boxes full of 'fixable' computers and parts every day.