Sounds like a West German Police carbine
based on the description of the rear sight. The occupying US Army turned over M-1 carbines to various police forces in Germany after the war. Most, but not all, were retrofitted with a Mauser style rear sight, that was siliver soldered to the receiver ring. The original dovetail was then filled in with a machined filler piece, then grooved across the top to prevent glare.
These police carbines all missed the the post war USGI rebuilding program, as they were in Germany. Hence, you wont ever see one with any post war rebuild items installed, unless a owner here added them on.
They are usually all matching, or very close. Most had the USGI stocks and handguards replaced with beech replacements during the 1950's.
The flat bolt BTW, should be blued. If its been parked, it means its been through a rebuilder at a US arsenal, or might be a post war replacment part.
I have no idea what Bavarian's (as some call them) are worth these days.
When I get them, I like to remove the blade sight, machine out the replacment filler piece on the dovetail, install a USGI rear sight and repark the lot. After adding a USGI walnut stock and handguard I then have a WW2 spec carbine, or what appears very close to one.
Some folks consider the German police carbine collectable in thier own right, and thats cool too.
HTH