Hi friend and congratulations,
You are referring at M-1 by Olympus, I guess; if so, I know it is a great piece for collector.
It was the same/early OM-1 at first introduced on the market as M-1; but since "M" was already a sign claimed by Leica, they had quickly to change it into "OM".
Hard to find M-Lenses separately; yet M-1 series, though collector-pieces, do not sell by too high prices: I know a couple of guys who bought M-1 by EUR 400-700, here in Italy.
I'll have a touch with them
, asking about lenses; later yet.