I've read on various ML forums that fabric stores , namely JoAnn, haven't had the widest selection of fabrics (100% cotton, tight weave), specifically, pillow ticking* that they once did. Yesterday I discovered that is the case, at least locally, if you're looking for .018" (compressed) ticking, as they only had a partial bolt in stock and none of the thicker outdoor type. Worse, the thinner, i.e., .014" - .015" blue striped ticking looks and feels exactly like the [slightly] thicker stuff I was looking for: It's a good thing I brought my micrometer with me else I'd have been out of luck! Don't get me wrong, JoAnn still has a nice selection of denim, which is a tad thicker/heavier than what I need; plenty of muslin, which is thinner than I want (.015"), and cotton duck, which is exactly what I was looking for. If you're thinking about purchasing fabric locally, do yourself a favor and bring a micrometer or dial indicating caliper with you as it will help you quickly determine which fabric are suitable for your needs + it will help avoid unnecessary purchases too.
*Gone were the pale green and brown striped ticking, which typically is .014" - .015" by my measurement.