Did an on-line search though several replacement magazine sites. Looks like an Norinco made magazine is going to be about $36- $39, but at least a few places list them.
As i remember the 9mm version, they used a steel plate pinned into the grip frame to take up the space and the magazine was pretty much the same as the 7.62X25 vesion, just made to 9mm length. Have seen a 38 Largo (think of a .38super case that is not semi-rimed but rimless) conversion where that spacer plate was removed, bringing the mag. well back to 7.62X25 size.
At one time I had two, one a 1967 Vietnam bring-back in .30 Tok and one of the Norinco imports like yours. Could mix and the parts, they are basically the same gun except for the barrel and the magazine (and if I took out that spacer plate in the 9mm, the 7.62X25 magazine fits fine).
So i had to try the 9mm with the 7.62X25 mag full of 9mm's. Well, there is too much for and aft space for the shorter 9mm rounds, the rounds can stack up oddly, so there is an occasional failure to feed.
Besides being a strong design, having a unitized trigger system (the whole trigger unit comes out in one piece), it has steel guides for feeding. the magazine just brings the rounds up to those machined steel guides.
9mm was sold or traded off, and the .30 version was badly rusted externally in Katrina. Was packed with RIG for long tern storage, so the internal parts survived..and the chrome bore survived. Parkerized it, so now it is even uglier than before, but still functions just fine.
Has a few small high vel. impact craters on the right side, so i assume the last Asian owner was a little too close to something that went "boom" and gave up all earthly interrest in material things. Someone had a set of wooden grips made (still using the metal spring bars to hold them onto the frame like the originals).
Whatever the wood was, if bare wood, and you hold it in your hand long enough, will peel your skin. Some SE Asian version of poision ivy? A thick coating of marine varnish cured that problem (I didn't want to replace them with originals as those villiage made grips are part of it's ugly charm).