Gotcha. Then the paperbacks might be the way to go. Haven't read Vol. 3-4 yet, but it's a shame the hardcover trim is not consistent in the series. Even if the book design was different I would've settled for a uniform oversized trim.
I'll still keep an eye out for the Book/Blu/DVD slipcase, though.
Here are some pics of my paperbacks, along with an example of what I consider "standard" trim:
As you can see in the first picture, the Black and White volumes are a wee little bit larger.
But as the second picture illustrates, Vol. 2 is slightly larger than Vol. 1.