Sorry to disillusion you Bear, but it's vinyl, not leather. I sold one off my blue ST1300 2004 with us both thinking it was leather until he tried to do a dye colour change.
Having said that, it's a high quality vinyl, and Bagster make them in France. They seem to wear very well.
They're distributed through UK supplier and cost about $230 landed. I don't have the price on the Bagster tank bag, but it's also very well constructed and matches the tank cover perfectly. For the ST1300 it is designed to flip up easily for refuelling.