High end AK-47s are usually higher in cost due to availability (Or lack of availability) not necessarily due to the performance, type, or military "Correctness".
Many former soviet countries produced the AK47 (And Later AK74). These ranged from exact copies to versions that parts will not interchange.
Currently there are even some US manufacturers. I dont have one, but I've "you-tubed" and handled a Century Arms Version "The C39" THey are now making a version 2 and stamped version (AKM).
I've owned several makes of AK, I like them, but the AK is a scaled up "Sub-machine gun / assault rifle" in its military form (Select Fire). In its civilian form, semi-auto, it is a reasonably accurate medium range rifle, some will be better, some will be worse.
As far as a "Military AK", the Yugoslavian, Romanian WASR, Bulgarian, Polish and Russian examples are "Correct" for the Cold war. The Warsaw Pact included all of these countries behind the "Iron Curtain".
Personally, I would not spend 1,000 + for an AK, unless I was a collector, knew what I was doing, etc. Otherwise if you want a "Military" AK you can get a good copy for 500-750 current prices.