When you have a variant that can be sourced from different vendors, you may find each vendor charges a different price. The "cost compare" column allows you to view each of the different cost prices to help you make an informed decision about who to buy from.
The column is available on these reports when in variant view:
Enabling cost compare
To enable the "cost compare" column, go to your desired report, make sure you're in variant view, then click the gear icon on the upper right-hand side of the page and click on the "cost compare" column.
If a variant is associated with more than one cost, you'll see each cost listed in the "cost compare" column.
Meanwhile, the "cost price" field displays an average of the individual cost prices from associated vendors.
Creating a purchase order when multiple costs are available
When you select variants and click "+ Multiple stock orders for [x] variants", Inventory Planner will chose variants with the minimum cost price for each vendor by default.
When you create a purchase order for a vendor and there is another one with lower cost price, Inventory Planner will show a message in the "Qty" column in a purchase order.