Retail Price on PO - Why?

If you do not have a Purchase Price on an item record and you have not yet entered a PO for the item (therefore no Last Purchase Price on the item record), the default price on your first purchase order will be the Base Price or Online Price, depending on what you have populated.

Here's the problem - If you enter a Purchase Price on the item record, that price will always trump the Last Purchase Price. So if you prefer to leave the Purchase Price blank and always use the Last Purchase Price (more accurate, keeps you from always having to update the record with price changes), you are going to get the retail/sales price showing the first time you enter a PO for the item. Your employees would have to be able to spot that it is the wrong price and correct it.