The very hard to find, and therefore very expensive carbines are ones that were never rebuilt after the war and all the parts are there as when they left the factory. If you find one of those and want it, be prepared to pay over 1k depending on maker and condition. For example, the Winchester M1 Carbine, with all original parts and in excellent condition will cost $2500.
The reason these are so hard to find is that after WWII most of the carbines made their way back to the arsenal. They were stripped of parts. The guns were then put back together with whatever parts were grabbed out of the pile. So, to find a Winchester carbine that has all W marked parts and all the right variation of parts for when the rifle was built is very rare and hence commands the higher price. Also, some parts like the front band and the rear sight were updated and the old parts were never put back on the carbine during the rebuild. Seeing a carbine with the bayonet mount/front band and the adjustable rear sight (as opposed to the flip rear sight) are sure quick and easy signs that the gun has been rebuilt.
Unless you want to spend the big bucks you will be looking for a rebuilt carbine for around $600-900. Rockola and Winchester I believe are the most sought after of the common makers. Inland produced the most and are the least sought after. There are several aftermarket makers. Too many to list but there are plenty of websites with that info on them. Plainfield made some early ones using all GI parts. Those would be the best aftermarket ones to look for if that is what you want. Do not waste your money on a Universal as they are not even the same design and do not use all mil spec parts. Hope that helps.
