eBay has them - there's a lady in spain that does them quite cheaply. I use to get them from Inch's aswell but don't think they sell them anymore.
If you type the web address on a label, depending on the exchange rate they can be cheaper to.
I would say the material is equal to, if not better than pikeur/cavello, but the seat is not leather or immitation leather, but looks somewhat similar.
The best bit is that the seat stretches and is lined, so they stick to the saddle but not to you!
Anyone who has worn pikeur/cavello all day in the summer heat will appreciate this!