Etsy has lots of unique and affordable options when it comes to jewelry. You can use keywords about her style and whichever type of jewelry you are considering.
I took a quick look for autumn witchy earrings, and I found a ton of cute options. I will share some of what I liked below, but of course you know her tastes best!
This is great advice. My partner does this, and he surprised me with an alexandrite ring I was drooling over. I was so delighted when he gave it to me, and it was such a thoughtful thing to do.