I have about 40 pounds of clean, freshwater gravel substrate available for free. Originally bought at Petco on Sports Arena. Converted my 29 gallon tank into saltwater, and rinsed the gravel very well. The gravel is natural river stones, medium sized, with white, black and grey colors. Pickup is in downtown S.D. Looks like this:
http://www.petco.com/product/105752/...in-Malibu.aspx