I am looking for an exclamation for a situation like the following:
You are disappointed for what there is or you already have, and then you unexpectedly find/discover something that is so different and is truly pleasant for you.
In such a situation you might say ‘this is what I was looking for for so long’, or ‘this is what I wanted all the time’, ‘this is my thing’, and alike.
I can think of ‘wow’. But I am looking to see if there is any other ones.