Tim, once you get on Zoro's mailing list you will get emails like this. "From us to you, 15% off your next order". This was a today only offer. Sometimes they have 24 hour sales as much as 30% off.
They are wholly owned by WW Grainger and sell the same stuff cheaper. Grainger has gotten on approved vendor lists of large companies and charges them out of the gazu. Zoro sells the same stuff a lot cheaper in a competitive price market.