Andrea,
Depends on what you are looking for - but a good starting point would be "A Time for Trumpets" by Charles Macdonald.
I am also a huge fan of the "After the Battle" series, so if you have $50, you may want to pick that one up too. Lots of detail, and lots of photographs - in fact, I can recommend all of the After the Battle books that I've read so far, including Market Garden, Fall of the West, and the Bulge.