What are the prices of each catalog in USD?
select catalog_entry_id, price_in_dollars from catalog_contents
What is the one with the highest price?
select * 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 desc limit 1
How about the lowest?
select * 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
What is its catalog level name?
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