We often see questions like "How much are my stamps worth", "how much should I bid on a collection?" I've been doing a little data gathering on this and was going to post in a couple weeks, but yesterday I saw a couple
ebay auctions that were so overpriced I decided to move up my timetable. Shown below is a table summarizing data I've gathered from
ebay sales and combined with some personal experiences.

In this chart I show the type of stamp container, the number of stamps, the average value in cents, the lowest value, the highest and the number of collections in the category. I should point out that this is a work in progress and I am limited to auctions where the number of stamps is stated.
For the beginner I will point out that there are a couple things that affect the price of stamps other than the catalog price which is often the focus. When there are a large nunber of stamps involved the manner in which they are presented affects their value. When there are a pile of glassines all full of stamps it is difficult to see what is included how much duplication, how many stamps there are, and of course you can miss that rare stamp everyone is looking for, so the stamps are worth less. If you take these stamps and spend the time to put them on stock sheets they would be worth a little more. Going to the next step and putting into an album makes the stamps even easier to evaluate and worth a little more as shown in the chart. Of course when the stamps are put into an album most duplicates are eliminated and this further complicates the calculation.
Other things that affects the value of stamps is what I call the density. If an album is 90% full it clearly includes more valuable stamps than if the same album is 25% full so the value per stamps is higher. The album, the period covered, the overall condition and other factors will affect the value but I think the table above is a good starting point.
Now let's look at a few collections;
http://www.ebay.com/itm/A-Z-WORLDWI...AOSwknJX12yDBased on my chart above an average price for this collection is $294 with a range of $138-$506
Here's another one;
http://www.ebay.com/itm/A-Z-WORLDWI...AOSwFdtX12eHBased on my chart above an average price for this collection is $160 with a range of $75-$275.
Obviously a dealer can set any price they want but I think informed bidders may think these two collections are not good value.
Here's one that just popped up on
ebay.

Based on my chart above an average price for this collection is $412 with a range of $193-$708. So this one has possibilities.
While this method may be helpful it is severely limited because only a fraction of the collections listed on
ebay include the stamp count.
I can look at a collection and quickly estimate how many stamps are included but I can't do that from a
ebay listing because sellers don't show sparse pages.
It should be helpful for those that want to know the approximate value of their collection.
Sorry for the long post I hope someone finds it useful.