The line_item.price field is required by Shopify when doing an import. If you try to import an order without a price Shopify will send back an error. The price must also be numeric, if you provide a value for the price that is non numeric you will get an error during import.

For most users providing and mapping the line_items.price field to a column in your CSV file that contains the price isn't a problem. However, there are situations where the price may not be available. For these situations, you can let Shopify map the price of your line item to the price of your products. To do this, you can simply click the Link product by SKU checkbox in the Custom Configuration section and leave the line_items.price field unchecked.

When you have the Link product by SKU option checked the line_items.price field becomes optional. This way Shopify knows to use the price of your product as the line_items.price. To learn more about how to link your products by SKU click here. Don't forget to map the SKU field when linking your products by their SKU.

There are two things to remember before using this feature.

1. SKUs are case sensitive. This means, the SKU in your CSV file must match the SKU on your product exactly. If the case is incorrect the product will not be found and the title will not be mapped.
2. If the SKU can not be found, the order will not import. The product information will come back empty which means the price field will be blank. Shopify will respond with a "price cannot be blank" error.