If I had to hire someone to build my MVP I would rather focus on design than creating a killer app on the first version.
This is why.
Since the service is not popular, doesnt have many users or features, I would try to convert users by offering them a great user experience.
Thats why I would invest 3k on a great UI/UX design and the rest on building the app.
There are good templates that you can use to give you decent design.
Realistically, it will be very hard to get a "great-looking-and-functioning" MVP on a $5K budget.