Second hand might be your best bet, if you consider that to be ethical. We got a set passed down to us and it's so much nicer than what we could afford. It's stainless.

Those are amazing pots. Beautiful, tin-lined. Just the way they used to be made. I would be so proud to own them! However, you will need to polish them, wash them by hand, and be wary of high temps with the tin lining--modern copper is usually lined with stainless, and tin has a low melting point. You have to use oil in an empty pot and salt will pit it. I would just be sure you are aware of all these things before investing in a whole set.

We love copper, it's just so beautiful, but ultimately went for stainless because of how easy it is to use. Our one "non-stick" pan is antique cast-iron, which weighs less than most modern cast iron. we also realized as we lived with our pots that we cared less about a matching set and more about how the pieces performed.