Alternatively if you want to filter by category please use https://www.kobo.com/au/en/search?Query=&fcshowpointsprice=n... As the main link gets modified by OzBargain and breaks this functionality.
If you don't want to use the Kobo app to listen, for Android the files are in
Android > Data > com.kobobooks.android > files > audiobooks
For each book there's a folder with a long string of characters, inside are numeric files with no extension. If you add a .mp3 extension, it should play in your preferred player. (Note: the files have no metadata)
All the audiobooks seem to all be published by W. F. Howes, so this might be a pricing/listing mistake.