Hi,
Well it all depends on what resources you allocate. The current free allowance is under $5, basically. So if you stay under that, your invoice should be $0. That should cover a couple of the smallest shared CPU vms, for example. Those ones should be sufficient for a side project. From that screenshot it looks like you may have allocated more resources e.g 1GB of RAM (I haven’t done the maths). As such the bill increases faster and you head towards exceeding the included free allowance.
Make sure your vms are shared cpu and have only 256MB of RAM assigned. And you create a single volume with maybe 1-3GB.