I have recently found about 1000 stamps dated from the late 1800's & early 1900's. How can i find their value?

I would think that you need the services of a reliable philatelist

who you can trust. (Not some guy in the back of a pawnshop)

He should have reference books that he can look up your stamps in. You may have some valuable stamps, so keep a good inventory on them when leaving them for appraisal.

Antiques Roadshow!

There are several books at the library or book store that will address each individual stamp and its value-Scott's is one of them.

An honest association of "Philately" in your area may be able to help you with that.

You can go to an antiques store and ask them.

http://www.glassinesurfer.com/

Start here. And you can Google "stamp collecting."