One thing I’ve learned over the years dealing with PC tech is that spinning drives is the one thing you absolutely don’t buy second hand. Plus, you can’t find 4TB or above drives second hand here. People use them till they die or repurpose them.
Second hand PC parts are generally overpriced here. People wanna get like 70, 80% of the price they paid for them. There are some reasonable sellers, but as I said, they usually don’t sell drives or sell drives that no one would need anyway (250GB, 500GB, 1TB spinning drives).
Your last suggestion is kinda good to be honest, I might opt for that.