Buying Diamond ETC band manager card option

Buying ETC band Diamond legendary Card option.
Hey I took a break during Festival of Legend expansion. Therefore, I didn’t buy Diamond ETC band Manager card. I am hearthstone loyalty and I play hearthstone since during OLD god expansion. You can check my account history that I spent a lot of money on hearthstone. So can you do a favor that give me option to buy Diamond ETC band Manger card because I like this card a lot. Please also I citizen of Azeroth and big fan of WOW.