For quickie gaming figs, I came up with a great method years ago:
I went down to my local rock and ready mix construction outlet. I took an empty plastic cool whip bowl with me. I told the guy that I was going to do some landscaping, and I wanted to get a few samples of construction sand. I'd have to "run it by the wife" of course.
I got a whole cool-whip bowl full of relatively fine construction sand. For free. And I've only used half of it to this day. I attach it to the base with PVA glue (That's Elmer's to us here) or just wet paint. Looks great!
Enjoy!