I have heard a lot of pigments used to weather, but not exactly sure what it's really is.

Someone care to enlighten me? As you can guess weathering isn't my strong side...

Let the truth be known......
If you go to a really good artist supply house, you can buy all the colors you need in containers much larger than the "model manufactures" sell them for. Of course the "Model Manufactures" really don't want modelers to know this. Now since all dry pigments start out as dry pigments, the only difference will be how finely they are ground. That's where the price difference at the artist supply house comes in for same color pigment. The finer they are ground, the more they will cost. (I really don't believe the happy after-market manufacture is sitting at his kitchen table with a mortar and pedestal grinding his own pigments!)
Two of the brands that I use are Gamblin, the other is Sennelier.
Of course the "Dry Pigment Model Manufactures" have their custom mixes for dust, rust, etc, but if you can mix basic colors, then you can mix your own dust, rust, etc.

Earth tones-which is the majority of what colors we use, are the cheapest. Last time I bought a few bottles of them it, ran me between 4 to 8 dollars-US each for 4 to 5 oz containers. (I remember paying that for the 1 pound containers back in college).

Of course this will probably start another dry pigment war-.... but I'll still go to the artist supply house, and still mix my own.....

Hi Becky,

Check out this article by Mig Jimenez (the owner of MIG Productions) and manufacturer of, IMHO, the best model pigments on the market.

Check it out HERE

To add to what Dave said, the price of the pigment is also determined by quality and how "clean" it is...

Rudi

p.s. Roderick.... so glad you "concur"...