At the moment there are some available on ebay for almost half price:
http://www.ebay.co.uk/itm/GENUINE-CITRO ... 1349013563" onclick="window.open(this.href);return false;
I had another slight shock when I decided to replace the fuel filter, which is the original.
My car has a sealed unit where you have to change the whole thing, though the advantage is I guess that there's no danger of getting dirt into the fuel system.
The list price is over £60, but oddly enough the best price was on Amazon at just over half that. The part number is Purflux 582.
Hope this information is of use.