I stopped in about 4 Home Depots in Southeast PA. None of them had Southdown (called 3 in South Jersey, no dice either). I've heard of some people using Kolorscape (in a blue bag) which is distributed by Old Castle and I found some of that, so I bought it. After I drove 6 bags 800 miles home I found out that they did not pass the vinegar test. A number of people on RC claimed they did the test and it worked... maybe 2 different sands bagged and sold under the same name? I was too much of a whimp to try it out in my new 90. I was thinking about keeping one, trying it out in the 29 that I'm slowly turning into a reef tank, and returning the rest to the Home Depot here (I think they have to take them back regardless of if they carry it or not). I know it won't buffer the tank, but I'd be interested in if there were any other drawbacks to using it.
Anyway, if someone is interested in them, I have five 40 pound bags that I'd sell for $6 a pop. That's about what I paid and about what I would get if I took them back to HD. If you want them, let me know ASAP, because taking them back was going to be a weekend trip.