That's assuming the domain name is available to register. Domain names likely to generate high revenues are unlikely to be available to register, and will have to be purchased.
Of course, over time, I'd expect revenue and expenses to converge...
with no contac link or onwership link, how would one go about finding out if the owner of the site would sell that name?
Start with WHOIS. If the owner is interested in selling, there will be at least a working email address in WHOIS, perhaps a working phone number and/or postal mail address, and perhaps even a clever "for sale" notice.
Of course, not all parked websites are owned by domain professionals - many are owned by people who know little to nothing about the web, had an idea, and didn't follow-up on it. If you are unable to contact the owner, they may simply be ignorant of the value of making themselves easy to contact, and you will just have to wait it out. These names will typically be parked with the registrar. (Since the owner gets no revenue from this, this is a clue as to the nature of the registration.) They will probably expire at the end of their term, and you may then be able pick them up by registering yourself or by subscribing to a wait-list service.
with no contac link or onwership link, how would one go about finding out if the owner of the site would sell that name?
As an owner of hundreds of domains (that I'll get around to developing ... some day) I get a lot of "would you consider selling" enquiries sent to the whois email contact.
But, many of the enquiries are clearly auto-generated, essentially spam sent to tens of thousands of domains on the off-chance they'll find one at a good price.
So if you ever want a reply from those sorts of enquiries, try to make it clear you're a real human interested in a specific name. One way to do that is to name your price in the opening contact. And make it realistic - a nice name that's say 6 years old probably isn't going to be sold for $50.
