I use the Billy bookcases as well in my office and I think they're pretty solid for what you're paying. I couldn't build anything of similar quality for that price or less once I factored in my time, so that's what I used. Another thing I really like about them is the cutout on the back so that they can fit over your trim and right against the wall!
What I did after setting them up though, is stack a majority of my console boxes on top of them to kind of have a display area and maximize the vertical space all the way up to the ceiling.