6.25 million carbines were made during WWII. After the war both foreign (Howa of Japan, Erma of Germany, etc) and domestic (Plainfield, Universal, Iver Johnson etc) manufactured thousands more. Commercial carbines pop up for cheap but the consensus is that they are not as desireable, durable, or reliable as USGI wartime ones. (The Howas would be cool since only about a thousand were imported from Thailand when the Royal Thai Police sold them as surplus, they are supposed to have been imported with royal seal still intact).
Where all the carbines are is the million dollar question over at the CMP forum. Maybe countries that bought them after WWII still use them but phased out the Garand when mag fed battle rifles became widespread. I have heard the Israel loves the 30 carbine round and have made a scaled down Galil chambered in it. Other rumors also say there are tons of Carbines in the Phillipines, Vietnam and other countries that are turning to rust because by law, we cant reimport them.
CMP forums are also saying that the Carbine barrelled actions are just that, barrelled actions. No bolts, sights, trigger group, oprod etc. I hope they at least have the gas assembly. No word on barrel condition or exterior finish yet.