ReefCrazy,
NMreef said "I've even tried with success a silica based playsand" this is the type of playsand that you will find at home depot. Mal also said that he was setting up a tank using Quickrete playsand if memory serves me right. Did you check the garden center at your local Home Depot, that is where you usually find Southdown playsand.
These are just alternative to that which you can purchase at your LFS.