The domain name market isn't like the housing market. Each domain name is unique and cannot be duplicated. A name that is worth $40,000 is also worth $15,000, but it is also worth $150,000. That is why appraisals are a scam and knowledge garnered from hours of studying every sales price you can is the best way to get a value. Also, remember that not every big sale is posted at DNJournal....some people like to keep that stuff private.
I believe that most any appraisal is useless if the person doing the appraising would not offer you 50 percent of that number right then and there (assuming they had the funds). Otherwise, you are stuck with a Jewelry-Type appraisal that everyone knows is meaningless.
If you go over every single sale over 10K in 2005 at DnJournal then you will have more knowledge than most.
Customer Service is the type of name that won't lend itself to a narrow range of appraisals, but I will tell you that it is a good enough name to hold out for a Home-Run....it definitely won't lose any value going forward.
I would only sell it to an end-user, even if I had to wait.