How can I find games by price in Steam?
If you go to the search page and click "advanced search", you can also filter for games under 15$, under 20$, and over 20$, in addition to the under 5$ and under 10$ categories.
Alternatively, you can just not search anything - that will display all games - and then sort according to price, by clicking the header of the "price" column. You can click it again to toggle between ascending or descending search.
Here's a direct link to page 5 of the descending link - where 30$ games start to appear - but as games are added and prices change constantly, the page in which 30$ games appear is bound to change.