SELECT t2.catalog_level_name FROM catalog_contents AS t1 JOIN catalog_structure AS t2 ON t1.catalog_level_number  =  t2.catalog_level_number ORDER BY t1.price_in_dollars LIMIT 1
Find the level name of the catalog with the lowest price (in USD).
[Schema (values) (types)]: | product_catalog |  Attribute_Definitions : attribute_id (text) , attribute_name (number) , attribute_data_type (text) | Catalogs : catalog_id (text) , catalog_name (number) , catalog_publisher (text) , date_of_publication (text) , date_of_latest_revision (number) | Catalog_Structure : catalog_level_number (text) , catalog_id (number) , catalog_level_name (text) | Catalog_Contents : catalog_entry_id (text) , catalog_level_number (number) , parent_entry_id (text) , previous_entry_id (text) , next_entry_id (number) , catalog_entry_name (text) , product_stock_number (text) , price_in_dollars (time) , price_in_euros (time) , price_in_pounds (number) , capacity (number) , length (text) , height (number) , width (number) | Catalog_Contents_Additional_Attributes : catalog_entry_id (text) , catalog_level_number (number) , attribute_id (text) , attribute_value (text);