In the 50s a company was willing to provide L.A. with a free monorail system, L.A. wouldn't have to do anything except allow it. The monorail company would keep all the fare money though.
The council turned them down.
There's also a few stories about parking meter companies wiling to provide meters for free to cities but they collect all the money until the meters are paid for plus a little bit and being turned down because the cities want the meters and the money.