If you want them to wip your fingers pre testing, then I would just was my hands, that's what I do. But if you want to use the wipes then most supermarkets sell them.
I have a packet of Diawipes in my meter wallet. It’s a miniature pack of wet wipes soaked in saline perfect for when out and about. I bought them here: https://www.funkypumpers.com/product/dia-wipes/