Also vacation.rentals in my opinion is about 500k overpriced and looking at the original sale, and its presence now, this is clearly a lottery price and the buyer's loss. However poor as the domain is it at least makes some sense. Yours don't. There are thousands of domains registered that have little to no value yet are still better than these. With regards to your question about how much you can sell it for who did you think your potential buyers were when you registered them? They are going to get no visitors and no coverage so you will have to actively reach out to people you think will want them to get any interest.