We found 2 Reddit comments about Saga Book Three. Here are the top ones, ranked by their Reddit score.
It's coming, but not until June https://www.amazon.com/dp/1534312218/ref=cm_sw_r_cp_api_Sdq-Bb48H3Z7F
https://www.amazon.com/Saga-Book-Three-Brian-Vaughan/dp/1534312218/ you'll have to wait another 6 months edit : I was not aware they made hardcovers for the volumes too.
It's coming, but not until June
https://www.amazon.com/dp/1534312218/ref=cm_sw_r_cp_api_Sdq-Bb48H3Z7F
https://www.amazon.com/Saga-Book-Three-Brian-Vaughan/dp/1534312218/ you'll have to wait another 6 months
edit : I was not aware they made hardcovers for the volumes too.