I haven't used one for about five years, and I haven't had a home computer with a functioning floppy drive (I did have one in the PC I used as a Linux server, but it wasn't connected and was probably so full of dust that it would spell instant doom to any disc inserted) for longer than that.
I don't recall how much they cost in the UK at first, because my computer at the time (a BBC Micro Model B) used 5.25" discs.
However, I do recall that, in the early 90s, the Student Union shop at University held the price at £1 for a 1.44MB disk for years after the price collapsed; presumably preying on those students too desperate, stupid or hungover to realise that you could get a box of ten for three quid in town.