I found a transformer/power source for something I wasn't using any longer. Just have to make sure it is 12v as a lot of items use various voltage. I then cut off the adapter that went into the device and used crimped wire connectors to hook it up to 3 pc case fans and then mounted them in the back of the cabinet with my home theater system.
If you are using a home theater receiver, they usually have an outlet on the back that only powers on when the receiver is on. I plugged mine into that so that when the receiver is on the fans come one and when the receiver is off the fans shut off.
Alternatively, plug everything into a power strip/surge protector to power on/off the consoles and fan at one time (not a bad idea anyway since apparently the game consoles use a fair bit of power even when they are "off").
Generic picture of a power adapter/transformer: just make sure you find a 12v one. I suppose you could also make sure the amps woudl be rated for your fans, but they usually don't draw uch power.