Radio Caroline
Pop music from a boat, because the BBC would not play it.
A ship anchored in international waters playing records all day, listened to under the bedclothes on a transistor radio.
The BBC had an agreement with the Musicians' Union that strictly limited "needle time" (hours of recorded music per day). So British teenagers got their pop from a converted ferry off the Essex coast.
The signal drifted, the DJs were young and unscripted, and it was the most exciting thing on the dial. The Marine Offences Act killed most of the pirates in 1967, and the BBC launched Radio 1 six weeks later with several of their DJs.
Cost back then
Free, if you had a transistor
Goes for now
Original Caroline merchandise £30+