My advice would be the "Equipment Exchange" here. Usually, the fellas have excellent guns for sale. I would definitely try here first.
However, it really depends on what they're looking for.
Arsenal Inc., (Las Vegas) makes quality AKs and you can find them from various dealers including; Jensen Arms, Atlantic Firearms, etc. Also, tell your troops to check out the Vector line of AKs. Now, if they're looking for pre '89 guns...good luck. They're rare. And, when you do find them, they're expensive as hell.
There are plenty of Romanian guns around the boards. Top quality and less expensive than most of their "cousins."
For instance, I just purchased a pre '89 Polytech (China) AK with underfolding bayonet. It was new, but I paid a pretty price. However, it was worth every penny.
We could really give you more information if we knew exactly what you were looking for.
Bud