I started with five old 1tb drives - gotta start somewhere and see if you even enjoy it!
You’re getting a lot of flak about your costs and investments and all that; just remember it is coming from people who have spent the last few months min/maxing and optimizing that stuff. Don’t worry about that too much if this is more of a hobby for now. Some people spend thousands on cars, boats, vacations, other hobbies, and those returns are near zero. So consider it a hobby, see if you like it, and learn and grow from there. You’ll naturally figure out the right balance for yourself. For example, some say get the biggest drive you can and don’t worry about cost per TB cause their electric expenses are high. Myself, I have very low electric expenses, so I use lots of small drives and I don’t pay more than $10/TB for used enterprise drives.
Have fun and ask more questions!