1. Create/Import Attributes and Values
2. Import Product Templates with Attributes and Values. This will create product variants. (Do not create variants directly).
3. Export your product variants
4. Fill out the internal reference, barcode, cost, and shipping weight fields on the exported variants csv
5. Import to update the existing variants
6. To import variant prices for more than one product template at one time, you will need to create a new menu item for product.template.attribute.value.
7. Once you have created the menu item, export all product.template.attribute.value records
8. Fill in the price extras and update the existing records via import. Take care not to create any new records.