The initial auction value was set at 15 gold coins, as Klaus thought that for less than this, it would not really be worth selling it.
Also, he was afraid that no one would bid if he asked too high for a price right away.
The deadline for the auction was set for one day, just as he had done with the Mutant-ranked Swift Arrows. Waiting a longer period of time for a better offer was very unlikely to happen. There was also the urge to be able to help his family soon, and he was in a hurry to get the money.
