For a tiny circuit board with a single 4-way connector on, this is pretty expensive, BUT the seller obviously has his hands tied because the cost from the manufacturer is correspondingly high. Having said that, it is superb quality and does the job perfectly - no hassle. I have not been able to source the connecter on its own, nor would it locate on standard stripboard anyway, so hey-ho, I'm not complaining really and I would still buy it again if I had the need. I'm happy!
If you want to converse an old analogue loco to dcc, I would recommend you to connect two wires to the motor in the loco and two wires to the pickups on each side. These four wires ends with a plug, which you connect to this connector in the tender. Then you solder the four wires from the connector to a decoder socket. Voila’ you are dcc ready!