Hello, First of all, .tk domains are free to register so a domain by itself is not worth anything unless it has some awesome keywords. Here is a list of domains I have registered: http://tk.siteproxy.org/status.php What do you think, worth anything? EDIT: If you have not guessed by looking at the list, they are proxy niche domains.
.tk is one of the crappiest extention out there, it's very well known as a free extention. Personally, I wouldn't pay money to reg any .tk names.