If you can't get your hands on Modern Backgammon, Robertie's 501 Essential Backgammon Problems is a great second choice. It provides the same problem/solution/explanation structure that Modern Backgammon does, but just without the theory sprinkled in between. It is also organized according to position type, which I think is more helpful. It's available from Gammon Press.
It's in fine shape. Half-serious, I guess. I certainly wasn't PLANNING on selling it or anything like that, but if the right offer came along from someone who really wants it I would.