Definitely save it for spells.
Casters don't scale as well with new gear like a melee class does.
And Intelligence-based pure casters have expensive spells.
You can budget for your next line of spells and see how much they will all cost and use any left over cash for gear.
There are some low level camps where you can earn decent cash at like the Sister Bandit camp in Lesser Faydark #14 on the wiki map:
https://wiki.project1999.com/Lesser_Faydark
That's good around 15 or 16 I think? I forget. But they drop Bronze weapons, which sell for a few plat each