In addition to other's learned remarks, there is also what is known as the "import" which really is a re-import (back into the U.S.) of original GI carbines that were "given" to friendly foreign governments over time -- mostly in the 50s and 60s... While you may land one that is a good shooter and can otherwise be cleaned up reasonably well (and therefore can represent a sort of bargain), they are typically valued much less due to their questionable/unknown history of use/abuse/neglect/storage conditions, etc--which is often borne out by their internal and external condition. Examination of some of these often reveals rough exteriors but perfectly servicable interiors..so they're worth checking out when you run across one--especially in this day of inflated prices on non-import GIs. These are usually characterized by a barrel with an arsenal stamp such as "Blue Sky" or sometimes no markings at all (i.e., no manufacturer - at least of the barrel - such as Inland, etc., and no date). While most experts agree that clean original (non import) carbines should be pretty much left alone - re reblue'ing, etc. - with maybe just some oil on the wood to refresh, etc., these "imports" can be a good excuse to ignore all that stuff and have at a nice restoration, with new wood, a re-blue'ing or parkerizing, etc. Doesn't mean it'll pay off in $$ in the short term, but you'll have a keeper in terms of pride and fun of ownership - for less.
Carbines that are all "original parts" like Corvettes with original numbers, of course go highest - asssuming good overall condition, but also some that are fairly rough. However, do not be discouraged necessarily by one that has gone through a "re-fit" which is what many did after WWII - to be, minimally, fit with updated safety (the flip variety that didn't appear til the end of the war), bayonette lug (ditto), and in some cases the windage adjustable ramp sight that appeared on most carbines after 1943--on 1942-43 variants. In addition, a refit may have replaced/swapped barrels or receivers, trigger groups, etc., of different manufacturers (original contractors). Since the carbine was designed to be nearly 100% interchangeable parts between all the contractors, generally this is no big deal - but shouldn't command the very highest price of the "all originals."
So, most of the "original looking" (not necessarily meaning original-original parts) GIs have been refit by now "legitimately" by a Government contractor -- and the above configuration (either with swapped parts or not) is what the preponderance of them ended up being headed into the Korean War.
If someone didn't already mention, IAI is a "true import" meaning Israeli Arms Industries (I believe I got that right)....they're "ok" but have the cheap birch - if that? - stocks of the lesser Auto Ordnance/Kahr models (which have a walnut option)...and are probably somewhere inbetween the Universals/Plainfields/Ivers and the genuine article. I am not an expert on these (or others for that matter), so others may chime in here to correct me.
)... maybe someone is hard chromng like the CZ-52's ???