If my friend asked me to make the aprons I'd ask her to prewash, dry and iron all the fabric. I would charge her nothing to make them. I would definitely let her know it's a one time deal and I'm only doing it because she is a good friend. I'm pretty much a shut in because of the Covid so I have a lot of spare time on my hands. Friends helping friends is a good thing, one never knows when a favor or help is needed.

With her buying the fabric I would say you are right in the price range you should be. $15-$20 is great!!

To me, $15 sounds good for sewing such a simple item.

Unless she wants ruffles and doodads, this apron should be quite easy. I think $15 is appropriate. And if she were a close friend, I’d do it for no charge.

She's actually one of my daughter's employees. I only know her through my daughter.

With that info, you might want to consider ........ what if she is not happy with your work, or your price, or any awkward situations that may come with you doing it for her .... then how might it affect the employer/employee relationship?

Or if you make these aprons for her, are you then setting yourself up for the rest of the staff to want you to do sewing for them too?

However, if you want to go ahead with it, perhaps your rate should the same per hour as this employee is getting!

All that said ... maybe it would be better to avoid complications and even conflicts, by saying no, before you are into something bigger and beyond what you want to be dealing with!