There has been some mild surprise expressed due to the presence of coffins for sale at certain Costco outlets in the area. The big-box discounter instituted the practice at a few of its stores in the East three years ago and the notion has spread, finally, to the Bay Area. A South San Francisco Costco is perfectly situated to take advantage of the option. It’s located within a few blocks of Colma’s cemeteries. So offering coffins makes sense there. Costco, for sure, is a one-stop shopping venue these days _ from cradle to grave, as it were. Can Costco headstones or special crypt reservations be far behind?