Hi, straight up, I'm the owner of the place I'm about to mention but I feel it's an interesting option for some travellers wishing to avoid the groups and guides and go it alone.
It is possible to get to machu Picchu very cheaply. We live and operate our homestay from our organic coffee farm "Yellow River" in a town called Quellomayo which is about a 6 hour walk (less if combined with a taxi) from aguas calientes. Getting to us costs around 50 soles per person by road (based on 2 people travelling together) and takes around 4 to 5 hours from Cusco's 'terminal Santiago' which has minivans going to santa maria and quillabamba.
A taxi from santa maria to us takes around 20 minutes.
From us to aguas calientes is a combinatin of walks and taxis and the two walks we always recommend to our guests are both very pretty. the first is from the farm to santa teresa and it takes you along the beach and riverbanks (only May to November during dry season) popping you out by the lovely natural thermal baths of Cocalmayo. From Santa teresa we always recommend a taxi to hidroelectrica as the road is dusty and ugly and this cuts out about 2 hours of boring trekking that adds nothing to anyone's experience of our beautiful region.
From hidroelectrica there is a daily train (about $18) to aguas calientes (35 minutes) or you can walk the rail tracks for around 2 to 3 hours (beautiful) and save the fare.
Our little bit is offering people somewhere to stay and appreciate a slice of peruvian family life after a long ride from cusco. Lots of people stay and do coffee roasting workshops or explore the farm. It's a good place to come after machu picchu too and some do decide to do Mapi first then come to us to wind down before heading back to cusco by road.
Hopefully by letting people know we exist it gives people another option. The inca jungle treks mostly pass through our village on day 2 anyway so it's part of the same route and we can always take you up to see the inca trail you would have hiked on that tour anyway. Hopefully you won't mind me posting this, just wanted to say hello and offer this as an idea. It's our wish to incentivise other local families to open up their homes to travellers so that some of the tourist money actually filters to the locals rather than going in the pockets of the agencies and more often than not the guides.
[ Edit: Edited on 28-Aug-2013, at 20:13 by quellomayo ]