Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_51 (sales VARCHAR, position VARCHAR, artist VARCHAR)

### Question ###
What were the sales for Dj Casper when he was in a position lower than 13?

### Accurate SQL ###

SELECT sales FROM table_name_51 WHERE position < 13 AND artist = "dj casper"