Freelancers aren't that expensive when you look at the grand scheme of things. A single freelancer can maintain an app serving thousands of users - provided you know exactly what you need.
Don't hire freelancers unless you:
1. Have done your customer development
2. Know which features you need
3. Know how much these features are worth to you
4. Already have something
So, freelancers might not be the best option for building your first prototype, but they are very good at polishing up your first prototype into a MVP.