I think what John is saying is that, for example, you can get a base for less than 10$ delivered from China. E.g. https://www.banggood.com/215mm-Height-M ... 28587.html
Or a dial indicator for a wee bit more: https://www.banggood.com/DANIU-40112302 ... 57267.html
Since the base has a magnet, is a bit heavy, etc. If he were to buy it (probably at similar cost, he won't buy the hundreds or more needed to get to a price break), he'd have to mark it up at least by the S&H fees. Also, it'll end up needing a larger box so USPS/Fedex/UPS/DHL will end up costing! So if John was able to put this together for less than 50$ delivered to Versalab (quite doable), it would probably double the price to ship it. Which will send it over customers/tax. At which point the DHL start charging their own handling fees. I think what he is doing is quite fair.
That is why I hated the belt. Getting it shipped to the Mediterranean was expensive. So I wanted to send two (halves the shipping cost each). But that exceeded the tax thresholds. Which added at least 20% to the cost and since customs didn't know what it was I had to go to them to get it released. Yuch! So I ended up buying one at a time or schlepp it through a forwarder. I may have been able to source it locally but couldn't spec it well.
I did the same building my 3d printer. Get all the motors, electronics and other stuff from China and only the printed parts from Europe/US.
The (abusive) Chinese post service make it such that splitting it into shipments so I don't get taxed was an extra benefit (here we have a 75$ tax exemption).
Scraping away (slowly) at the tyranny of biases and dogma.