The largest craftable bag of the current expansion is a permanent seller, and the whole subclass tracks the cloth market that feeds it.
Bag (Container)
Auction-house prices and price history for Bag in MoP Classic.
69 items in Containers › Bag are currently auctionable in Mists of Pandaria Classic.
Prices refresh daily from TradeSkillMaster (TSM), so day-to-day gaps in lower-volume listings are expected rather than a collection problem.
Bag listings link to price-history pages with per-realm buyout, average, and median data for Mists of Pandaria Classic.