I think you can sum it up in 'supply and demand'.

I can source most things that I need for restoration either in the UK or Europe including horn, exotic wood, bone, brass rod, nickel silver rod, all types of thin metal sheet and any tool I need. I recently found (from Jamie) a supplier of G10 in a decent range. The things I buy from the US when required are micro fasteners, pivot bolts and paua/abalone sheet for scales. The problem with buying sheet material is the ridiculous carriage charges that Macecraft apply - it was something like $60 last time I ordered - and that was for about four sheets of 8x5".