The rifles only have crufflers as a market. The bayonets have several potential buyers, including those who live in countries where they can't own a working version of the rifle, therefore supply is lower.
The K31 is also facing an issue with matching magazines. K31s bridged the era of "one mag serialed to the rifle intended to be recharged by stripper clips, and the "new school" interchangeable and disposable box mag. Since they are detachable box mags that work in the usual manner, the original K31 mags are often "replaced" by aftermarket ones by "less scrupulous" sellers. Since these serial numbered magazines will often fetch about 2/5ths to half of the value of the rifle, I can see why this practice exists even as I find it distasteful.
The K31 is also facing an issue with matching magazines. K31s bridged the era of "one mag serialed to the rifle intended to be recharged by stripper clips, and the "new school" interchangeable and disposable box mag. Since they are detachable box mags that work in the usual manner, the original K31 mags are often "replaced" by aftermarket ones by "less scrupulous" sellers. Since these serial numbered magazines will often fetch about 2/5ths to half of the value of the rifle, I can see why this practice exists even as I find it distasteful.