I'll just point something out.
For less than $1k I added a remote fob for my thrusters (bow and stern). It controls thrusters only. No engine control.
That does allow me to step out onto my side deck and use the thrusters to steer into the slip once the boat is basically lined up and creeping in. But need to duck or reach inside to bump the throttle.
And then once in place in the slip, to move around to tie lines and use the thrusters remotely to keep the boat in place while I do so.
With no throttle control that isn't nearly the function of a fully remote dock mate or similar.
It is an inexpensive middle ground that for the modest cost is something I find well worth it.
As far as connectivity goes, I never lost it in the half season of use so far, including while moving around on the dock. It does time itself off after about 15 minutes of no use so its useful to just bump a thruster now and again until you know you are done. If it does time off its only a few seconds to hit the buttons to turn it back on.
There's no doubt that one can engineer their own wireless docking controller from readily-available components, varying in quality, reliability and price from cheap consumer-grade gadgets to serious industrial controllers. Adding wireless thruster control to previously fixed-control boat is a big improvement, but the real magic happens when adding gear-shifting control, giving the helmsman full wireless positional command of the vessel even when standing on the dock. Adding CANbus interfaces to newer equipment brings a few more layers of complexity, but is still reasonably accessible for those with enough motivation.
My company started out exactly that way, with much experimentation testing a wide range of off-the-shelf products. We quickly learned that membrane-switch transmitters (and especially those used in mini key fobs) would not be able to provide the safety factors we wanted for our products. The reliability issue perhaps isn't so acute when controlling only thrusters, but becomes critical when adding gear control.
The largest differences between consumer-grade and industrial controls are that the latter are configured with dry-contract relays so that different equipment functions (for example: thrusters, propulsion controls, windlass) are each handled using their own source signal voltage, and with safety circuitry to shut off the base station from any input to the connected equipment when the OFF/Emergency button is pressed. The top-tier industrial controls (priced accordingly) also include multiple redundant relay bridges to guarantee absolute certainty of equipment disconnect, so that there is no way for one or even two stuck relays in series to allow the connected equipment to remain engaged when transmitter signal is lost or the OFF button pressed. None of those safety precautions exist in cheap consumer-grade products, where the possibility of relay that cost pennies getting stuck -- though thankfully rare -- is considerably higher, and without the additional safety equipment could result in a very expensive mishap.
For these reasons we optimized our wireless docking controls for maximum reliability, which means in part that we've stayed away from fancy-looking little transmitters with delicate joysticks and thin membrane switches, instead staying with more substantial components both in the base station and the handheld transmitter.
Still, none of my comment here is intended to discourage the adventurous from experimenting and engineering their own wireless docking controls, but simply to encourage careful consideration of potential failure modes, and to build in some additional protection for those scenarios. A properly-implemented custom solution can certainly be assembled for much less than the premium Yacht Controller prices I've seen quoted recently, but the true cost of such a system won't be at the bargain $1000 price-point either.
Custom-engineered solutions can be a lot of fun, but they're not practical for the vast majority of the boaters who would benefit most from the technology. Fortunately there are other product alternatives without the US price tags of Yacht Controller or Dockmate.
