Crossbows are the rarest ranged family, so a single strong crossbow listing can be the best available on a realm for a long stretch.
Crossbow (Weapon)
Auction-house prices and price history for Crossbow in MoP Classic.
55 items in Weapons › Crossbow 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.
Crossbow listings link to price-history pages with per-realm buyout, average, and median data for Mists of Pandaria Classic.