When importing products an error came back with "12.99" as incorrect also, upon adding only 10 lines in the spreadsheet (that was downloaded) it said lines 11 and beyond there was an error... they were blank?
Response:
The valid values for the "PRICING_MODEL" column are SINGLE, VOLUME, CATEGORY, SKU, and BID. You will want to put the "12.99" in the "PRICING" column.
I recommend downloading and using a fresh product import sheet to solve the blank lines issue.