In the first instance, just ask as one human to another if you can track down contact details - you might surprised. I went through something similar recently and it all worked out amazingly, although I don't imagine my experience is the more common one (the owner basically said 'i tried something with it but it didn't work out, good luck' and gave it to me).

Thank you for the advice, you were very lucky to get your domain, your experience isn't indeed a common one, but I'll try it, worse case could be the guy could rising the price just because of my interest.