It's rare that I say, "WOW" anymore to interior design...but,
I know more than a few parents who would love to have such a well planned space for their kids.
Let's think about it, you don't need expensive built ins...
All you need to do is center the bunk beds in the middle of the room, against the wall, with a desk on the left and right with overhead shelving...
Of course, measuring is the key to success here...You must make sure that your bed and two desks will fit on the wall in question. Paint or stain them all the same color accessorize with wall lighting, art and viola.
A good resource for custom built, wood furniture like bunk beds and bookshelves is Gothic Cabinet Craft