When you buy the leather knob from Fiat as a spare part you get the leather gaiter with it. I know, I bought a black one.
Well knowing now that the gaiter is included makes the £67ish sound better value. I think the black gear stick looks strange with the Ivory ambience so will hopefully make this change in the next few months. Let us all know how you get on changing it over. Good luck.
I you are still looking there is one on ebay for £25..
http://cgi.ebay.co.uk/Fiat-500-5-Speed-Gear-Knob-Ivory-2008-Onward-/390311908450?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5ae0671462#ht_500wt_922