IF YOU HAVE THE NORMAL ONES, DONT CRAFT BY ANY MEANS THE GOLDENS. ONLY if you want to collect the goldens and dont care if you will lose gold. If you want to make profit and crafted the normal ones dont craft the goldens
Let's say you have 4800 dust. You craft the normal one and then you decide you want the golden. Wasted 4800 dust. Now the expansion comes and you get your refund. You get only 3200 dust because you get rewarded for the maximum amount of copies you can put in a deck. That's 1 for legendaries. If you have 1 golden then you will be rewarded for 1 golden. So you wasted 4800 and got refunded 3200. Still 1600 dust minus. Let's say you keep the golden and dust the normal. +400. That's 1200 minus but you got yourself a golden legendary for 1200 dust only. Let's say you dust it too then you gained +1600. That's 400 dust profit. But why would you craft them both then dust them?
Let's say you have neither and craft normal. Then the expansion comes, you get refunded 1600, same amount as you have spent. So you got yourself a free legendary. Let's say you dust it. Then +400 free dust for you.
Let's say now you have neither and craft only golden for 3200. You get 3200 as a refund. And a free golden legendary since you had no profit or loss. Let's say you dust it? Then 1600 free dust for you