Amazon! I have the same one, I got it over Christmas last year to sketch in. However, it's not a good sketching journal and I use it for notes now.

I'll find the link, but I'm fairly certain if you just search Amazon for a "leather journal" this one, and several like it, will show up.

Edit: Here's a link, but I'm sure there's many more sellers of the same journal. Additionally I've seen it in witchcraft-like stores.

Keep in mind it's little. Fits basically in my one hand.

Apparently this is the "newer" version on Amazon. Don't know what that means, but it's DEFINITELY BIGGER. Just pay attention to the sizes.