What I usually do is firstly use domainnamepro to find out who
owns other tld's to the domains I want to sell. Depending on situ
I send them an email simply asking of they would like to buy xyz
domain. IF I have .com and they have .net and it is a bit
"dodgy" then I write and say "I wonder if you would like to sell
me xyz.net since I have xyz/com and would like to have both" .
That usually results in a contact and they say they want to
buy the .com.
DG