I tried that for the old part number on Amazon and eBay and unfortunately the sellers (who were dealers anyway) just confirmed it's no longer available as it was shipped from the manufacturer anyway and not an item off the shelf. Dangit, I might have to just go aftermarket!
Did you search the Yamaha part number on ebay? That's where I found mine for 200 and free shipping. It seems really high quality and the UHMW plastic really slides on rocks and is quiet when it happens.