I agree with your $10 estimate on Zytel mags Jake.
What some people may not know is there is a difference in Zytel mags. The pre-bans generally work OK, but the post bans can be very problematic. An easy way to tell is a close examination of the Cobray logo. It will be raised/embossed on the original magazines, while the post bans Zytels are pressed into the material.
We went to great lengths back in the day to improve the PAM2 magazines. Jake headed up what may have been his first group by on replacement springs. If memory serves correctly, they were Wolff springs designed for use in the 32 round Uzi mags. Where is provided much easier loading without sacrificing reliability. Coupled with the Zytel follower clones Richard made, these were the best mags we had even if they lacked an over insertion stop,
The first PAM2s I purchased were from Jerry Prasser wayback when cost about $17 each. The last batch I bought were from CDNN and priced at $9.99 each. I keep talking about the good all days, being right now. This may give you a little insight as to why I keep saying that.
I’d be inclined to swap the followers and springs from the Zytel mags into the PAM2s and keep them. Otherwise I think $10 for the Zytels and $20 for the Argentine PAM2s is about right.