Just to clarify, petfooddirect and nationalpetpharmacy are the same company. Why they do it that way, with two different sites.. No idea. If I need something, I often check between the two to see which site is offering the better deal that day.
I'd like to add a word of caution for those buying bags of feed from them. Better stock up before they catch on and nix the $5 shipping deal. When I first started out, the native earth was less than ten bucks a bag and shipping was very reasonable. After I ordered about five bags, they cranked up the price and the rate. That's when I finally went and found myself a local dealer for rat feed.