I got mine (long gone) in 1973 for $250, with a 50mm Summicron collapsible lens. It was quite old then (I seem to recall that I once looked up my serial number and determined my M3 was made in 1954; same vintage as me).
But inflation since then has been a lot; a random online calculator says my $250 is now worth $1391 (and looking deeper into the ebay search, that bottom guy is an optimist).