Heh. Hard to take advice from someone that's got an ulterior motive, but I would suggest a pre-made drop-down case. The weight of the bigger LCD will be a pain for making hinges. Also, I've seen bigger drop-down screens and they seem akward to me.
Now for the second part, how much do you want for that 15"?
I've been watching for a good deal on a 15" for some time now with no luck.
I keep trying to steal my wife's LCD (400 nits brightness!) but she guards it too closely.