SKF make a kit containing two tensioner bearings and both belts. This comes in about $130, roughly the same price as a single tensioner bearing from Citroen.

The kit number is VKMA 03010. The box says it's for a 1300 engine but the 1220 engine takes the same belts. There's also a kit listed for the 1015 engine, which is different.

The bad news: Wongy at Auto France says this kit isn't available in Oz. I'd suggest ringing SKF with part number in hand and asking why not. Otherwise, mine came from Alan Sklenars in Hamilton, New Zealand.