You'll need a bit more than 50$ to jam them for an aircraft, though

Depends where the plane is.

High altitude, away from any precision navigation areas, not a huge risk.

Flying a GPS approach to an airport - definite risk.

Bear in mind that a GPS satellite has a power budget of ~4kw, and it's >12,000 miles up.

A jammer may only have a watt or two of transmit power, but it can put all of that into a single channel, and it's only going to be a few miles away from your receiver.

You're off by around an order of magnitude:

https://apps.fcc.gov/els/GetAtt.html?id=110032&x=.

Transmitter power is only 25W. EIRP is ~450W.

Of course. But then you'd have to do it while right next to an airport, which is a quick ticket to jail.

In practice, the aircraft will do a go around then proceed with ATC vectoring or inertial navigation.

Ah no. Directional GPS jamming is quite effective with an easily sourced satellite TV dish, a tripod and some straight forward electronics. You can even point it at a plane using their own ADS-B signal.

PPDs are omnidirectional, but quite hard to precisely geolocate when intermittent and moving, as was the case in the well known Newark events (which shut down a major airport).

Airports with difficult approach (like the old Kai Tak in HK) could easily result in CFIT with only small errors, let alone other aircraft.