I like building prototypes which might only have less than 10 users but need to be deployed to the public. Often I use dynamodb because the cost of this kind of load is nearly nothing, but because with dynamo you design your schema based on access patterns, I don't find it well-suited to a prototype where the access patterns change all the time. My problem is the relational dbs I've seen cost usually a min. $40/month, which is too much, especially considering I often have 10+ prototypes at once. Any ideas?
Have you considered spinning up a cheap Linux box from any VPS provider and deploying your own relational database of choice there? Sure, there will be more administrative overhead for you than there would be with managed solutions, but it will be cheaper in the long run. In your case it sounds like you might be better off just spinning up a weedy Linux box on DigitalOcean, or Vultr, or some other cloud provider and just use that.
Would highly recommend Railway (https://railway.app) for this! Entirely serverless, meaning you pay for hardware usage, not the hardware itself. Most DBs that I use for small projects end up costing <$1/mo (which sits well under their free plan).
