Here's one I bumped into looking for YouTube performances on brand name violins. I saw a student performing this and looked up the composition, Corelli's "La Folia" Sonata on YouTube and found these. There are two versions. I have included some sheet music below. Some sections are approachable for the student.
This is pretty complicated, and I hear, a little modern in interpretation. Still, awesome.
This is still pretty tough, but more baroque
Sheet music for the first,
For the second,