Just couldn't resist this one any longer!  Rosi, don't feel you stepped on any
toes - it's just that buying shells isn't like buying most "normal" retail
goods, but involves a surprisingly large number of factors such as general
helpfullness; accuracy of descriptions and grading; overall speed of
transaction; care taken with completeness and accuracy of data slips; finding
things from your want-lists; price in comparison to other dealersp;
variety/selection; what part of the world, or what families a particular dealer
specializes in; whether they make good on mistakes quikly; what sort of items
(sets, one-of-a-kinds, large, showy shells, top-quality shells, unusual or
interesting items, odd-ball stuff, etc.) they regulary offer; how their lists
are constructed; ease of navigating their website; quality and quantity of
pictures/images - the list is nearly endless!!

As Frank has sagely suggested, the best way is just to a) decide what you want
in a shell dealer, and b) shop around until you find a few dealers that you are
satisfied with, based upon your personal needs and preferences.  I would add
also, c) try a new dealer or two every now and then - you might get a pleasant
surprise sometimes!!  This is just not something that can be "Rated" very easily.

From the Great Wet North (but, is it ever GREEN up here!!);
Ross.