Agreed.
ebay is your best option.
My suggestions are based on this being a collection of US stamps.
For the best results, make sure you take lots of photos of the early stuff & use a hosting site to post them. The more photos, the better. Additionally, try to calculate the face value of all the mint stamps from 1940 on. With a few exceptions, modern era US stamps will sell for less than face value. If there are any high face value stamps from the that era (for instance: Scott 1053, $5 Hamilton), be sure to include those in your descriptions & photos.
Finally, modern era used stamps (1940 on) will get the least attention. Don't spend much time photographing those ... just include a photo of the whole lot and something in the description like: " x thousand used stamps from 19xx - 19xx."
Hope that helps!
Brian