Hello, I was wondering if there was a way to change the cost of spells with sp, for instance say a spell cost 200 sp and you wanted to change it to 1 sp

Yes, that is the "worth" property of spells. So add something like this to spells.yml

blink:
  worth: 2

If a spell was inherited would I have to go back to the original?
accio:
worth: 5
category: charms
inherit: pull

No, anything you add to accio will always override whatever is in push.