In general, appraisals of $0 to "Reg fee" indicate it may be difficult to sell your domain for more than what it costs to register a new one. Actual registration fees vary from $6.95 to $35, which is why I prefer the term "no premium value".
For example if we are valuating a domain where there are similar quality names still readily available for registration, I would consider it to have no premium value over registration fee.