I thought I'd put this circuit together on paper while waiting for Mary to finish pushing the sucky thing around.
A visit to your local recycling centre should yield a free power supply, you only need one.
The breakout board is available from Banggood. Again you only need one.
The switch is a simple changeover, you'll need 1 for each points set, I think the supply is good for at least 20 servos
These switches can also be found in a centre off, and even as a double changeover.