All links to accessories are through Amazon.com. You can purchase items from any source if you do not wish to purchase from Amazon
A sheet music stand is vital for holding your sheet music or method book at the proper height for good posture while playing. Most students use a folding wire stand at home but they can be a little flimsy, especially with a book. So maybe you go a little beefier with the solid metal stand like the ones we use at school.
An instrument stand allows your student to spend less time each week with assembly/disassembly and more time actually playing. Students are also more likely to practice on their own when they see the instrument sitting out on a stand.
Here are a few items that are inexpensive upgrades for instrumentalists. These items are of a better build quality than the items that come with student-level instruments, so they're either more comfortable or they help create a better sound. These are also great options if your original item breaks or is lost.