In order for a buyer to purchase a domain from your domain shop, he or she will need to go through at least 2 pages. The first is the landing page, the second is the fulfillment page.
Landing page, as the name indicates, is the first page the visitor lands on after typing the domain name into the browser. It can be either a sales page for the domain or a stand-alone lander. Either page should have the domain prominently displayed. The eyes should be drawn straight to the domain name. The page can also include other details such as usage, age, a sales blurb, a way to contact you as the seller, and, of course, a prominent Buy Now button (if you set a price) and/or Make an Offer (some prefer Request Price) form. The landing page is part of your front-facing website for the public.
The fulfillment page is where the buyer initiates and commits to the purchase. In most cases, this page is hosted by the payment processor, such as Escrow.com, PayPal, Stripe, etc. Also, the fulfillment page can be on a third party mainstream marketplace with internal capability to process and disburse payments.
When it comes to fulfillment pages, you can offer buyers to use the option they feel most comfortable with from the landing page on your domain sales shop.