The one bandpass box I have laying around was quite good for a pre fab box...the front half of the box is made of particle board, and the back half is made from MDF (3/4" all the way around) Overall it is a pretty good box.
I HATE the 10" sealed q-logic box that i have.. leaks like a mofo. but then again i have a wicked cheap sub inside of the box... but it still shouldn't leak.