Unfortunately not possible to buy it separately.

You can only buy different ones but neither of them have magnets: https://www.razer.com/shop/keyboards/gaming-keyboards-accessories?query=:newest:category:keyboards-accessories:keyboards-accessory-shop-by:Wrist%2BRests

@FiszPL Thank you so much for the fast reply. Good to know I wasn’t blind and it wasn’t there. Are there any wrist rests that are similar that you would recommend?

I have the same issue, I have two Ornata keyboards and both work great but have extremely worn wrist rests. I am very disappointed and confused by the idea that Razer does not offer a replacement without the keyboard! I work using an electric sit/stand desk and other wrist guards always get out of place when going from a siting poster to standing and back. I guess we could try the non magnetic one they sell but the lack of the mag lock is keeping me from trying it out. 

Well, me too. No Ornata V2 palmrest as spare part means no more Razer products will be bought...