It's not the paying users that determine who is interested in the product. It's the value you add to those who are traveling. When you highlight this with your messaging and channels, it creates a difference in who responds and how.

I know from working in the travel industry (and traveling myself), that there is a lot of value to the app that specific target markets would go for. But you have to identify who they are, what customer journey they go on and how (as well as when) they would respond to you and become fans. When you map that out, it will become easier to target and use specific channels that get results.

I can help you more, if you would like. :)