You don't really have to worry about buying 'live' sand, especially from Ebay. Sand is frequently listed on MAAST by people taking down thier tanks, and usually a LOT cheaper than online, especially when you factor in shipping. And it doesn't have to be live sand either. If you have live rock, it will seed the sand and make it 'live'. Also, there are plenty of people here that you will give you a cup or so of live sand which can also seed your sand. Once seeded by something, it will take on a life of it's own.

My sandbed is plain Southdown (probably not available around here anymore) topped with a small layer of I don't remember grade aragonite sand. The live rock seeded it, and you've seen how alive it is now. You probably don't want to put Southdown in an existing setup because it will really make a mess of you water until it settles. Stick with a reef grade sand. It's cleaner.

If you feel like a trip back to Lockhart, I'll give you a cup or so of sand.