When balancing homebrew, it's worth looking at existing systems that it will mimic.

Special arrows are not unlike spells. If you hit, they do their thing, if you miss, they do nothing but either way a resource is expended. In the case of a spell, the spell slot is expended.

Then compare the cost, lets use Melf's Acid Arrow as an example.
Lvl 2 spell takes 100gp of materials (inks etc.) and 4h for a Wizard to copy it into their spellbook. They must also find the scroll/other wizard's spellbook that contains it. Once learned though it only costs the spell slot.

To make an equivalent mundane arrow, I'd suggest a similar time commitment to make some*. It should probably cost less than 100g to make since this cost is required for every arrow, but more than 50g which would be the spell level below. It would definitely require some acid though so harvesting/purchasing that would be a separate issue. I'd probably allow the crafter a skill check. Intelligence (woodcrafting or alchemists tools) would be permitted. The result of the skill check would determine the number of arrows crafted before the materials/time is exhausted.
10-14 = 1
15-20 = 2
21-25 = 3
26-30 = 4

Side-note, it should probably not properly replicate the effects of the spell exactly or you're getting into dangerous territory when they want to make fireball arrows! For those, better to look at the alchemists fire or grenade items for a template.

If they were making poison arrows I'd allow poisoner's kit of course. I wouldn't recommend trying to get too rulesy about this, see what the player wants to do and make a judgement call. Allow the player to make suggestions but don't be too permissive. With the basic structure outlined above to keep to you