Invalid_key_or_ref: Import failed for SF record id <the id is specified>.
Reason: Invalid price reference key -1 for item.
This means that the product(s) on the Opportunity has not been synced to a NetSuite item.
Find the NetSuite id. Edit the Salesforce Product to include the NetSuite item id. Edit the NetSuite item to include the 18-character Salesforce id.