Hello there,
as D360 says, Oct/Sep are ideal months as the weather in the Andes could not be better; no rains, no cold, no tourist crowds. Also, many flowers bloom at this time of year macking the andean senery even more colorful.
I like the comments below, if you have time and little money, and know spanish, then it is easy to get around Peru. But do remember that Peru is still a 3rd world country for a reason, things that should be easy sometimes are difficutl. For example, you can purchae your train to Machu Picchu tickets once you are in Cuzco, but it will take you an entire morning just to wait in line and the service is horrible and frustrating.
You should see what we offer and we can coztumize all our packages to fit any traveler's needs. Feel free to visit
www.peruforless.com and ask questions as you wish.
Enjoy!