I need to know where I can find value of stamp collection. Some date back to late 1800's early 1900's.

Answer 1

From Harry McCulloch, President Glen Ellyn Philatelic Club:

A few words of caution.
The value of any stamp collection depends heavily on the condition and the
format of the collection. There are a lot of "very old" stamps that have "very little"
value.
You could do a self-evaluation using one of the following methods:
1) "Fast and Dirty"- applies to worldwide stamp collections - count the number of
stamps in the collection. Multiply that number by $.20 (twenty cents) that is the
"base catalog price" for stamps in the Scott Catalog. Then multiply the result by
.3 (30%), which is the typical discount a dealer would apply to make an offer.
2) "Face Value"- mainly applies to U.S. Stamps and involves counting all the
mint (never used) stamps by value and adding up the result. This is the
postage value of the collection. This method can be used on foreign stamps but
would require the ability to covert to U.S. currency. A dealer will usually discount
face value by 50% (or more depending on condition. For a recent collection
donated to the club, my inventory at face was over $100 and the catalog was
over $500. We gave the donor a letter thanking her for a $200 donation to youth
philately.
3) Cataloging the collection - Means what it says. Getting a current Scott Catalog
(available from most libraries) and identifying each item by Scott number and
listing the catalog value.
Because the donation mentioned above was "small" this was the approach that I
took for it. It took me about three hours to identify and develop a spreadsheet to
establish the face value and catalog value of the stamps.
A professional dealer could do it a lot faster because he/she would only look up
the "special stamps". Again, given the Scott Catalog value, a sale would
probably not get more than 30% of the Catalog value.

Other considerations:
Any sign of dampness is a big negative. (30% goes to 20 %)
Any mildew or musty odor is an even bigger negative. (30% goes to 10%, or 0)
Loose stamps are worth less
Stamps in “envelopes” of any kind are worth less
Stamps properly mounted in albums are worth more.
Mint stamps that are hinged will be valued at a number between mint and used.

Answer 2

Lou has lots of good advice, but I'd like to add in a non-commercial website that is very helpful: http://www.virtualstampclub.com/inherit It will answer many of your questions, and it doesn't matter if you inherited the stamps or got them some other way.

Answer 3

Go to your local library.
Do the research yourself,don't trust anyone online.
Until you do the research
There are many many dealer books published on these type of subjects ie stamps,coins,baseball cards etc.

good luck
chris

Answer 4

Go to a "philatelics" Website.