subman:I would also recommend that you get some 25 cents samples first to check the color & size.
It would also probably be a good idea to apply some of whatever bonding agent you intend to use to the ballast samples to see what the color looks like after it has dried.
A friend of mine had purchased quite a bit of ballast for his railroad (I think from Smith and Sons) and was happy with the result. When he needed some more, he ordered the same flavor. But when he applied the same bonding agent to the new material he found that it had dried an entirely different color. He later determined that even though the new ballast was labeled as being the same as the old, it had been "mined" from a different quarry.