Have you heard of IMSLP? It stands for International Music Score Library Project, a site dedicated to preserving electronically classical music literature. If you’ve been instructed to purchase a particular piece of music (or a book of etudes!), give this website a look first. I have found many different sources of etudes for my students, and even if you’re looking for something different to play, this is a great resource. Enjoy!
International Music Score Library Project
Here’s one my favorite finds thus far- a beginning violin method book by Charles DeBeriot.