Another important point that is often overlooked is that there are no restrooms inside the park. Combine that with the very limited reentry options, and I would strongly advise against excessive eating or drinking before heading up the mountain. One regular water bottle should be enough to bring. If you do go for the AM ticket, book one of the mountains as well. It gets hot fast up there, so the 7am hike is far less brutal than the 9am.

Considering the absurd food costs, I decided $40 for a good buffet in a nice hotel is a much better deal than $20 for a sandwich at a counter. But that was back when one could leave the park for lunch and reenter in the afternoon. Perhaps it might be better just to head down at 11 and grab some lunch in town.

As for Aguas Calientes, it is really one of the most miserable tourist-hell places that I have ever been. The hotels range from poor to mediocre, while the food is not much better. Best bet is to arrive in the late afternoon, go to bed very early, and wake up in time to be in line for the bus before 3 am. Take an early afternoon train back out of town and do not look back. However, $1500+ for a night at Sanctuary is not within the budget of anyone who has a budget.

Also, if you are self-booking, make sure that you exchange the online Machu Picchu bus voucher for an actual ticket from the ticket booth as soon as you get to town, because they do not open until well after the buses start running in the morning, and the voucher will not get you on the bus.