BB Hunter,
The 2500 number is good for the Remington 700 Classic limited edition for each year. Remember that there is a 700 Classic in standard and Magnum chamberings that is available at any time. So for example, a 30-06 classic will be readily available in very large numbers. The 700 Classic yearly limited editions are actually made in the Custom Shop as opposed to the regular assembly line.
As far as other brands go. I have called the Ruger factory about some of the rifles I own, they will give you date of manufacture and where it was shipped but they will not give out how many of a model they produced. I have a 77RSC in 458, that I would love to know the production number on! The Ruger #3 is definately a collectors item. They were chambered in 44 mag, 22 hornet, 30-40 krag, 375 winchester and 45/70. The 375 Win and 30-40 were very limited in production.
With Winchester, you can generally get production information as far as when made, where shipped and how many chambered from the factory with a "Factory Letter" or from the Winchester's Collector's Association/ Cody Museum. Both of these options involve a charge of about $50.00.
I hope this information helps you in evaluation of your guns. The good news is -- they always seem to go up in value and they don't eat too much!