Found these 6 magazine in my stash.  

Are these the "flat back" magazines that everyone refers to?

6 mags total.  
The four mags on the left are heavy comoline.  The first 3 of these 4 are used, with the 4th one looking new.  
The two on the right are used and both of these have "china".  
Are they all Chinese or only the 2?
I tried taking pics of all 4 sides.  Any markings I should be looking for?
How much is each one worth?  






Mags 1-4


These are the 2 mags on the right:


The are the two on the right:

All Chinese, and the 3 unusual ones are the rarer all-stamped mags that have stamped feed lips, look to be in good shape too, those are keepers for sure!

ETA: and two of the regular flatbacks there, have 3 witness holes on the back, which I think is also a little rarer than the single witness hole models.

So the one with the stamped feedlips are the 3 on the left?

Correct. They are a cool bit of AK history, a nice addition to any AK mag collection, I picked up one in good condition off the EE not long ago.

Thanks!!

Prices vary with new importers bringing batches in.

Jg sales had a huge lot a few years ago and they were 10 bucks each, the same price as all the rest.