I am an another one who is looking for the Walpier Buttero at a competitive price and have found some during enormous contacting, but they are not a wholesaler. Visit Etsy and find the shop, 'Myleathertool', have a look their leather products. Seems they are just retail shop, I presume that's why they can provide competitive price. However, that's the only one what I have found at the moment. Thankfully, they provide whole leather hide skiving service for free. It would be helpful for the stuff whatever you would make, and they are also selling a Walpier Authentication Certificate currently. (around $3 USD, a request required to seller for it)
Before you make the order, you may must find out the custom policies for importing leathers because it may be quarantine issued, of cause it depends on where you leave.
If I've found a better one, will let you know. hope you get the best result of your work mate.