A proprietary valve on a Vaillant boiler started leaking. This is just outside the boiler often called the “trim” which connects directly to the boiler’s proprietary union joint. Europe does not seem to have standard generic flared fittings.

When I asked Vaillant sellers for a replacement valve (which you might expect to be under €10), they say the valve is not sold separately; must be bought in a kit that facq charges €92 for and some shops charge ~€65 for.

The right to repair requires parts to be affordable IIUC, so the old trick of bundling parts together to make the price unreasonable for a simple valve probably does not comply. But has the right to repair taken effect yet? That article just says that a majority voted for it. I’ve not heard that it is in force yet.