starro,
I think the K-12 kits are sold out everywhere. The K-8 is the replacement, but one set of measurements have not been good. No measurements for the K-16 yet, but there are some good subjective comments.
tubesandmore.com has the K-502 kit ($200) which is very similar to the K-12. I would choose the K-502 over the K-8.
Hope this helps.
I think the K-12 kits are sold out everywhere. The K-8 is the replacement, but one set of measurements have not been good. No measurements for the K-16 yet, but there are some good subjective comments.
tubesandmore.com has the K-502 kit ($200) which is very similar to the K-12. I would choose the K-502 over the K-8.
Hope this helps.