I bought two a couple of months ago direct from VESPE on their website.
I was a bit miffed to afterwards find that BOBCO had them cheaper than Vespe were selling direct.
As a clumsy sod I pleasantly found them easy to fit.
I did buy a cheap set of grinders to drill the pole as per the Vespe Youtube video. It made the job very easy.
Give the two sites above a visit.