I got a personalized Big Sister book for my niece and I just got it in yesterday. It's super cute! I love that both names are in it and I think my SIL will be excited. It was a little on the high side, but honestly, some kids books are around $20 nowadays, so it didn't bother me to spend a little extra for the personalization.
https://www.iseeme.com/super-incredible-big-sister-personalized-childrens-book.html
I highly recommend - I love that it's a hardback and the quality of the the book and ink looks great.
Re: Big Sister/Brother book rave
My sister got the "my very own fairy tale" book for DD's first birthday. She was a little young for it then but it's a cute book. I need to find it and pull it out again now. I was pleased with the quality.