Rare Cards in Yu-gi-oh?

[KJ_Jounouchi]

So I only liked the original Yu-gi-oh and I stopped watching it during GX. I still remember that the 3 Egyptian God Cards were super rare and expensive before but nowadays you could get it for $5 in amazon...

For those who watches Yu-gi-oh still with Zexal, what are the rarest cards now? Mind you, I don't play the game anymore and I'm only collecting the cards that brings me back fond memories. I'm also just watching the old, old Yu-gi-oh episodes... :3