If we were a big media outfit, this second-hand reportage might not pass muster. But we hear it from a very reliable source that Duane Reade was having a totally nutso sale today, with all summer stuff and beach paraphernelia 90 percent off. We’re talking fans for 99 cents; bags of potting soil for 25 cents; travel mugs, 50 cents; and small-to-medium-sized bags of charcoal, 60 cents. “One woman walked off with 25 bags and left me two,” said our tipster, who says the Cortelyou Road store is already fairly well picked clean. No idea what’s left at any other stores (Flatbush and Parkside said they’re cleaned out too) but it might be worth a stop on the way home tonight.