As Trading Assistants we see the gamut of merchadise come through our doors each day....
Usually we can evaluate the value of this merchandise in the blink of an eye, or possibly with a quick online trip to Terapeak...
But when something is presented by a client... say possibly a fine piece of antique furniture, do you get that uneasy feeling in your gut that says "I might need a real appraisal on this one"? 
If you don't get that feeling, you must have extensive antiques experience or your just flying by the seat of your pants. Not knowing the true value of any fine antique can cost you and your client hundreds if not thousands of dollars.
To sell an antique properly, you must know more than the projected value at auction of the piece. You will not get that projected value if you do not describe it correctly in your listing with all of the historical detail possible.
How do you get that information? From a book?
You could, if you had the time...
From Terapeak or Hammertap? - Not likely...
From eBay? - Please, you would be depending upon some other seller who may not know what he is talking about...If you could find the same exact piece listed at all... (Not likely with antiques)
How about from an appraiser? Yes a real, licensed expert in antiques appraisal!
Isnt that expensive? - Sure, locally you could spend quite a bit of cash on a certified appraisal, but what if you could get one completed online from your photographs?
With the same Seal of Approval and accuracy? Something you can take to your buyer with confidence...