Hi again, Insideout:
For U.S. stamps, the primary reference is Scott Catalogue and they are very protective of their copyrighted numbering and valuing scheme. So you won't find a catalogue online.
On the other hand, pretend you're interested in the catalog value for the 1933 American Philatelic Society Souvenir Sheet -- its Scott Catalog number is 730. Jump over to
ebay's stamp area and search for 730. As you scroll through the results, you'll find almost every seller is more than happy to quote the catalog value (CV).
The second part of the lesson here is that catalog values aren't really that meaningful. According to Scott, CV reflects retail prices (i.e. dealer overhead) and are based on stamps of a certain grade. So, bottom line, we all use CV for a reference point, but you will rarely have to pay CV when buying, and you will almost never realize CV when selling.
I don't collect coins, so I'm not the best one to give you a contrast -- but some of the other members here will have a better answer for you than mine.
Kirk
P.S. By the way, unless you live in a tiny town like me, you will probably be able to find the Scott Catalogue at your local library.
Scott has catalogs for almost every country. If you're dealing with Canadian stamps, look for the Unitrade Catalog. Someone else here will tell you why Stanley Gibbons is preferred by many worldwide collectors.
[edit to add postscript]
Posted 11/19/2010 6:21 pm
