If you’re looking to sell items online ... Use a credit card, and if possible, keep the sale within the platform it’s listed on. “You also want to make sure you try to stay in the platform itself.
The coin collection is listed on eBay for £20,000 or the best offer, and at the time of writing is on nine people's wishlists. Postage for the coins would cost £10.35 with Royal Mail Special Delivery.