I'm thinking of doing that as well. The only fine ballast they had there was brown though, and I think it'll clash a bit with the dark, stark theme I'm going for. The coarse ballast covers up the "snow" look to the base, so now it looks more like carved rock, which is where I'm going with it.
I also bought some fine grass effect, some green and brown enamels to go with the Dagobah set. I was going to get some of that fake water, too, but it only came in large quantities and I don't need that much!
I just have to remember to stick to ONE project, and that's my contest entry. I want to do it all NOW!