Like others have said, it is obviously a good name, and the challenge will be to promote awareness of it, get top search engine rankings etc because would I just go to my keyboard and type that name in? Possibly I'd type villas.co.uk or SpanishVillas.co.uk (or .es) or holidayvillas.co.uk but villarentals, while good, is not the only or instinctively the first name people would type. I'd be inclined to build up volume of villas by initially offering free advertising to get as many villas as possible on your site. Because if you just have 5 or 10 villas, people will look, but not bother to come back again. So I think I'd play the long game, make little profit the first year, but build up a resource that lists loads of villas for free. Then introduce a lead in to paid advertising for 'featured villas' and build up the paid element from there. (Or you offer publicity in return for a % commission.) But it looks a lot of work that way. Maybe you've thought of easier ways to develop it. Exciting name, but until it's developed, I'd suggest £6000 to £8000.
But others may well have more insight than me. If so, see if they'd buy it! But then again, I see you're not seeking to sell.
Susannah