Perhaps it may make sense to say something if none of resulting trips meet your search criteria.. For example, while I understand this isn't a realistic search, I entered '$300' and left the rest of the options as the default. All of the resulting options are 9x to 10x+ the cost of what I entered with no indication that it couldn't find trips matching my criteria better other than a 'relevancy' number that is hard to find in the UI because it does not stand out.