Hi and welcome.
NamePros is not a paid service. It is free, unless you would like to become a Business Member. In reference to a question about the pricing of domains, you will have first to do a good amount of reading here or in other places in order to learn what the value of domains is.
It takes time, but there are at least a few forums, blogs and other sources that might help you. My personal advice: Do not think of selling a domain name before you know why it is valuable (if it is).
Some sites you might benefit from visiting: Domaining.com, DNJournal.com, NameBio.com, etc.