Appraisals in general are really rough because its very difficult to determine potential sale prices. Your best bet is to look at Sales Comps of recent keywords. However, of the paid appraisal services, Godaddy is among the worst. I highly recommend posting in the appraisal section here at NamePros. Often times Domain experts will explain potential value and what you might be able to fetch on the market.
And of course, Welcome to Namepros
Justin