I can't speak for anyone else, but...here's what I would want the seller to do at a minimum.
I like the board in the pic above, all of the tiny electronic components are all in one place (instead of me needing to order them from three different vendors), and they are all soldered in the proper location on the board.
What I most want is for the brain-chip to be pre-programmed by the seller before I get it. It may be quick and easy for you, but I will pay for someone else to make sure that it is done right.
What I can easily do without screwing it up:
Cut square bar into proper lengths, drill seven holes in each, bolt bars to their proper place.
Make the four cables (I can source all the components for the cables locally)
solder-in the large single capacitor (too easy, just make sure the positive hole is clearly marked?)
Make all the tube standoffs (brass, plastic?...either is easy). I can also source stand-off tubes locally without any wait
Attach screen read-out
solder-in the adjustment dial into place
plug-in and solder that 6-pin "segger" device
If you add the raw square bar to the kit, that's fine, I can finish it off. However, you can make the shipping a little lighter because I can source the square bar from a local metals supplier (since you are shipping around the world). I just need the dimensions, and I can be working on it while I wait for your kit to arrive...You can have the cables as a purchase option, either a loose-part kit or complete, but...I can make those too, quite easily.
Sooo...is that all I have to do to take the kit from the first pic to end up like the second pic below?
[edit: I now think I would definitely recommend that you make the square-bars and cables available on your website as a completed product (cut and drilled), separate from the basic kit. However, charge a high price for those, because most DIY guys can buy those by themselves using local materials...no need for you to try to be competitive and get headaches over the easy-to-get stuff. The square bar can be found at onlinemetals.com, and you need to focus on the tech stuff, not brass bars and cables. I just bought a 3/4-inch diameter copper rod a foot long for $20, arrived in four days.]