I looked on my local craigslist to check (los angeles) and that seemed to be around the price that people had listed. There were a few up. I buy in bulk and have never tried to sell it so I am not completely sure what the issue is. Post on bulletins at the feed store around you perhaps?
Maybe try selling it in larger quantities also, at a bit of a deal. 1 lb of DE seems like a small amount for most people that use it with any regularity. This is food grade correct? Make sure your ad it is very clear about that.
You could also try in advance next time asking if there is anyone...