I need a HDD but they are expensive and I don't have that much money because I'm young. So I thought "What about an used HDD?" But do you think it is a good idea? Are there some problems I could face?
2.5 inch and 750 gb - 2 tbWhat size HDD are you looking for and capacity?
Used HDD's, I personally don't really dabble with them, mostly out of caution.
Anyway, if you get one, run Crystal disk mark on it and check if it's still functioning correctly.