Since 99% of hams literally no longer scratch build anything anymore this causes the: Gee does someone make a kit for such and such application. Kit building gives you the feel of being a real ham and not just an appliance operator. Kit building while also is a Flash the Cash is less of the unboxing a completed unit from "Chine" and more of a pseudo feel of I built this.
Antenna tuners are a good example and there are a couple of companies that sell fully automatic high power antenna tuners, and many have a hefty Flash the Cash price tag. But what if you wanted a kit as this suggests having the capability but at a lesser price. So, we consulted the House of Bozos (BoJack + Bezos) and found a plethora of low-cost 100-watt automatic and a bevy of kits (mostly QRP) but some rated at 100-watts where the Flash The Cash < $100.
Now if you are in the 1% who wants to homebrew a 3KW automatic unit then you could do it with stepper motors and Arduino code.
So, now you know where to find Automatic Antenna Tuners assembled for less than $100 or basic kits for under $50. That $35 kit just gets you in the door, but to see the fan dancer you need to spend additional $$$ for connectors, a case, a power supply and likely now beyond $100. But you get the extreme satisfaction of saying: "Look Ma, I homebrewed an antenna tuner kit."
Them that know can scratch build a high-power antenna tuner.
73's
Pete N6QW