Inland Division of General Motors produced the most M1 and M2 Carbines.
They are generally noted as being the best made, simply because they had more experience than anyone else.
Prices depend on whether it's an re-import like the Korean bring-back "Blue Sky" guns, or a Carbine that was a US surplussed gun.
The second factor is condition.
As a rule of thumb, an "average" of about $600 and up for a good non-re-import Inland.