How to order a custom

I’ve seen a seller who makes beautiful jewellery and I want to order a custom from them but there isn’t really a way to do this on vinted without risk to the seller as I can’t prove that I’m going to buy it before they make it. I believe it’s against the terms to ask for PayPal, Etsy or some other way I could pay upfront so not sure how to go about it! Please let me know if you have any tips, I know vinted isn’t the platform for this but they don’t have any social media linked so not sure what else to do !