One thousand top-grade magic crystals was already a very high starting bid.
Within the Underground Colosseum, pricing varied depending on a cultivator's cultivation level, and this particular price was typically reserved for cultivators at the Golden Core (mid-stage). The cultivator up on the stage awaiting auction was only at the Golden Core (early stage) and looked half-dead to boot, so he really shouldn't have commanded such a high opening price. It was only because he possessed a single wind Spiritual Root and striking good looks that they had set the bar so high.
Those who frequented the Underground Colosseum were rarely short on money. Given that face, anyone with a penchant for men would throw in a bid, exorbitant starting price notwithstanding.
Chapter 300