Error 73: The price in the listing is either invalid or below the minimum price.

The 'Buy it Now' price input into the Item.BuyItNowPrice field (or into the Item.StartPrice field for 'Fixed Price' calls) must be equal to or greater than the minimum value. The minimum 'Buy it Now' price can vary by marketplace and category, but in the US, the minimum price for fixed price listings is $0.99. This error can also be triggered if a 'Buy it Now' price is set for an auction listing, and the 'Buy it Now' price for an auction listing typically must be at least 30 percent higher than the starting bid price.