How do you handle performance at such a low cost? I don't know any $5 cloud that has enough RAM for the database, let alone the app. It would run, but seems like it would have to be really slow. If it doesn't its own node and was shared, that would be different. Still tough at $5, though. Maybe if you don't use cloud computing but use containers on hardware without HA you could squeeze the performance from $5 of slice.
Digital Ocean or Vultr
DO is good, we found in tests that Vultr and Linode had the highest performance compared to DO and everyone else. The same $5 would go farther there. For comparison, though, on Vultr or Linode we need an $80/mo instance to handle the performance needs of NodeBB. We are a busy site, $20 would be good for most. But just be aware that at under $20 of hosting cost, you are looking at a seriously underpowered system.
At a $5 instance, you'd be limited to Redis only and constantly swapping. For $5 on DO or Vultr you get only 1GB of RAM. Total. Our NodeBB uses over 9.4GB of RAM on a dedicated node for comparison.
And at $5 that's assume every penny goes to the cloud host. You'd need money for the install and maintenance, then for the profits. So presumably using the $3.50 instances which are just 512MB of RAM. So you can see the concerns.