On large international forums such as this one and others where the majority of users are not from the UK, it's always best to work in U.S. Dollars, that's my point. If you are posting domains on AcornDomains for example, of course, use UK Sterling as that is a British site with the majority on there being British domainers, buyers and sellers.
I would also recommend that you list how much time is left with your domain registration. If, for example, you had registered your domain name as part of a multi-year plan, the buyer would be aware that he may not have to pay domain registration renewal costs for a long-time, increasing the value to him and the amount he may bid. Hope this helps.