First of all, Machu Picchu is sinfully over priced and full of pesky tourists. It became a cliche symbol of exoticism, a mandatory visit for all wanna be "explorers". Having said this, it is nevertheless entirely worth visiting and in spite all its inherent negatives it will leave you breathless.
We took a bus half way to Aguas Calientes just to save on some of the train fare. We still paid $120 each for a few km ride on a "fancy" train that ran on uneven tracks. The basic entry fee to the actual site was $50.
The city's architecture in itself is not extraordinary. What is stunning is the setting high in the Andes mountains. I could not get enough of the marvelous view and imagining what life could have been like 800 years ago.