Yarns that are not to be missed in a proper brick and mortar store

The basis of every successful brick and mortar store, besides any fashion, fancy and luxury yarns, are what we call "bred and butter" yarns that are very popular among a lot of knitters. We are not talking about "cheap" yarns, we are talking about classic standard yarns with a very good price-value-ratio. They, too, should be of top quality and have their reason for being in the range.