I did an exact search for “outdoor rugs uk” (I’m in the US) and there were six ads, not counting the shopping ads, on the first page. There are at least six paying candidates for you to target. In terms of valuation, check Google keyword planner for monthly search volume, CPC and CTR for the keywords “outdoor rugs” in the UK. How much would it cost to pay for all of those clicks per month if they all came to your site. Then multiply it by 12 and see what you come up with. Check on estibot how much type-in traffic your domain gets. Multiply that by the CPC and you can get a sense of maybe how much having the domain might save them in direct traffic. If there’s zero, you have to guess at their marketing budgets, but you must imagine it’s quite a bit if there are six ads (3 top, 3 bottom). So it really depends how much traffic your domain can drive for them. It’ll likely be used to redirect to their site. Because of this, you’ll likely have to price it around $xxx-xxxx.