Default Cost is a placeholder value for an item's wholesale cost that is used by Springboard Retail at certain times when an average cost is not available. An item's Default Cost is typically what you would pay the vendor to purchase the item at wholesale.
When you receive inventory in Springboard, the cost that you hold the item at is the item's average cost. An item's average cost can be different than its Default Cost because vendors sometimes sell the same items at different prices.
There are certain times when Springboard Retail will use an item's Default Cost, specifically when there is no average cost present. For example, if you have 0 on hand of an item and you sell it from the POS, Springboard Retail needs to record a cost of goods sold for that sale and will use the item's Default Cost to do so.
Springboard Retail will also use the Default Cost when a PO is being created. If the price on the PO needs to be different than the item's Default Cost, it can be overridden.