Let's clear this up once and for all....
...because there is still obviously a LOT of confusion about surplus Mausers.
Yes, Mitchell has for years been hawking post-war Yugoslav M48 mauser rifles. They are not German, and were not made during or prior to WWII. They are called M48 because they are the model of 1948 adopted by the Yugoslav Army. They look a whole lot like German k98 rifles from WWII because they were built largely on tooling that was previously used by Germany to manufacture the k98.
Unfortunately, Mitchell has used somewhat, um, deceptive wording in its advertising. They tout the M48's as "WWII era" and built on "German machinery."
The M48 is a very good rifle. Unlike real German WWII k98's, M48's are generally available in excellent condition, because most of them never saw combat. Tens of thousands have been imported and sold in "unissued condition." They are still available cheap.
The Mitchell ad in the current American Rifleman is NOT describing Yugoslav M48 rifles. Rather, it is describing real, German, WWII k98 rifles.
It is true that as recently as 10 years ago, real German k98 WWII-era rifles were relatively scarce. Collectors bought all of them, and their collector value was high enough that they were not considered shooters. That's because the only ones in the USA were generally those brought back from WWII by US vets as war souvenirs. That's not a whole lot of them, in the grand scheme of things. My dad collected German military Mauser rifles when I was a kid. He had dozens of them in various versions. Many of them were worth well over a thousand dollars each, even back then (the 1970s).
Starting a year or two ago, however, the market for German military WWII mauser rifles changed radically. The reason is simple. Something like 8 million k98's were built by Germany between 1933 and 1945. That's a lot of rifles. No more than 10,000 were probably in the USA until recently, however, so they were scarce and expensive. So where did all those Wehrmacht mausers go? They went into the arsenals of the Soviet Union at the end of WWII. And that's where they stayed for almost 60 years.
You all know that Mosin-Nagant rifles have flooded into the USA from Russian and other former USSR countries over the last 5-10 years. You can still buy as many as you want, in many cases for $100 or less per rifle. They are generally in good shape, because they were "re-arsenaled" after WWII and put into storage.
The same thing happened to captured German mauser rifles. The Soviets re-arsenaled millions of them and stored them. With the end of the Cold War and the opening of those countries to the west, lots of those obsolete arms became available for export. In the last few years, a number of importers have managed to put together deals for captured German mauser rifles.
That is what Interarms, Mitchell and others are selling now -- real WWII German mauser rifles that were captured by the Soviets. Many of them have been rearsenaled by the Soviets, and will show evidence of it (cyrillic markings, Russian proof marks, etc.). Many are quite common variants (tens or even hundreds of thousands made, and who knows how many survived). Because there are so many of them, they are cheaper now than they have been at any time since the Wehrmacht first procured them 60+ years ago.
The importers aren't stupid, however. They are going over each one carefully. Those that are in particularly good shape, and those that bear rare markings sought after by collectors (such as the SS death's head), are being pulled out and priced separately. What you will get for $500 is a run-of-the-mill k98 that was captured, rearsenaled and stored by the Russkies. It may or may not have rearsenal markings. The retailers/wholesalers will generally be able to tell you, and you may have to pay a higher price for matching numbers, no rearsenal marks, etc. It will not have rare waffenamts or unit markings at that price -- expect to pay well into the thousands for those.
The Mitchell describes the rifles as "near new" condition, with "like new bluing." In most cases, I believe, that's because they were reblued in Russian arsensals at the end of WWII prior to being put into storage. Note that Mitchell claims matching numbers on "at least six" major parts. Again, that's as much as they can claim, because these are generally re-arsenaled rifles. I didn't see any claim that they were free from re-arsenal or Russian capture markings.