Hey,
there are definitely people who can answer this question better as I am not overly familiar with budgeting but in general it highly depends on your cloud service and how they calculate cost. In general I would read:
https://slurm.schedmd.com/sacctmgr.html
https://slurm.schedmd.com/slurm.conf.html#OPT_EnforcePartLimits
But others might be able to point you towards more specific sections. I also want to point out that if you are learning Slurm for research, you might have associations in your country where you can apply for a small number of free resources.
Best,
Xaver