the more USGI parts its made with the more they are worth. but overall they are considered bottom of the barrel for M1 carbines. if its a restricted variant with the forked oprod (weird hole in it for the bolt lug) $200-250 if its still in good shape without any cracks in the oprod, if it has the USGI style traditional oprod... $350-400 if it's in realy good shape.
I know I wouldn't pay more. they were never particularly well made guns that just got worse overtime. Not like plainfields, they got better and better till the point were they weren't making much money off them because the build quality was such a high standard in the end lol.