Stamps (Philately)/1935 Scott Album
Scott wrote at 2013-08-28 10:47:18
There are a few things that may help as well. One thing that might be of use to you (if like me there are no "local libraries" with copies of the Scott books in them), you can go to eBay and just browse through what's selling there and for what. (Careful to not go by "Asking" price but watch a few, and see what they actually sell for). There's "Book value" which is what you pay from a dealer and then there's "Sell value" which is what the market really bears, especially when selling privately.
As another rule of thumb, anything after around 1940 if its Mint, (all those 3cent years) going to be valued at "TOP" rated conditions around 80cents each. Get in to around 1970's - 1990 and they will go down to about 40 cents each. From that point, I would take "face value" of the new stamp as reasonable "guess" of value. This will hold true for vast majority. If you have a "High Face Value" stamp from the 40's - 70's (say $1 - $5 for original stamp cost), these can have a bit more value. There are a few excetions to this along the way but if there are 1000's of stamps as you mention, more likely they are going to fall 95% into this category, in this timeline.
Now, stuff prior to 1940 gets interesting. 1900 - 1940 there are some gems. This is where eBay will help you a lot, and anything prior to 1900 treat has having a good chance of being worth "something", ranging from a few dollars ($3 - $6) to a LOT (Maybe even $2,000 if you have something mint, if used, usually around 1/10 that value).
Hope that helps you find a way to "guess" a reasonable range. One thing I shoot for is a "range" when estimating where I am 90% certain that my estimate falls in that range. Just a suggestion.