If you're near a gravel yard, try some mortar sand, about a dollar for 5 or so 5 gal buckets. Since you're going to lose the sand anyway, why use expensive stuff? Just be sure to get the drier sand from the edges of the pile or you will have to air dry it before you use it. I have had no problems with this sand and even use it in my blasting cabinet with a screen filter before reusing it.
