As I go through the process of building I'll blog the builds. There is lots of excellent documentation out there and the excellent site https://vnxx02.blogspot.com/ contains a lot of information and links. If you are challenged reading Japanese most browsers will turn it into reasonable English or some other language. There are build documents in English.
jl1vnq (at sign) gmail.com is the source of these kits not me.
They cost 8000 yen which is £57 today ($73) and that is without shipping and local VAT etc charges.
These are homebrew kits of a pretty high standard which do require the builder to be experienced in small component SMT construction, do not even remotely think this is anything like a K2 kit from Elecraft it isn't. They are cute though.
If you are used to a project coming in a plastic bag of components you have to sort out, you might be very surprised.
I am not recommending the kit to any and I am building mine for myself. Hopefully the build goes OK.
You might expect some support from other builders (if they have time) but don't please expect someone else to build it for you or fix anything.
The project has been out for a while and in development between lots of amateurs, it was featured in the JA CQ May 2019 so if you try to get one you might experience a delay obtaining one as I am sure domestic demand might be pretty high.
You might like to check out the CW Invaders project from Dai JQ1SRN - the CW Invader. Details from the rather interesting URL http://project59.blog.fc2.com/ and https://jl1vnq.blogspot.com/ (you will have to translate them) but keep digging details are there.
http://project59.blog.fc2.com/blog-entry-656.html - manual here too. It's in Japanese though.
Or you can get the English one here