Domain owners behind WHOIS privacy are not necessarily unreachable. The privacy service has to offer some way of contacting those domain owners by proxy, so you may just have to fill out a web form behind a CAPTCHA to get your message across.
I did this for a domain a few weeks ago that was using OpenSRS' WHOIS privacy (via http://contactprivacy.com) and while it took 2 weeks for the owner to get back to me, he responded by putting the domain up on Sedo so I could make an offer on it.
I did this for a domain a few weeks ago that was using OpenSRS' WHOIS privacy (via http://contactprivacy.com) and while it took 2 weeks for the owner to get back to me, he responded by putting the domain up on Sedo so I could make an offer on it.