I've spent the last two weeks in Germany for no more than $10 through a volunteer opportunity called Workaway. The process for getting one of these volunteer gigs is:
Tomorrow is my last day of work at a farm in Saarland, Germany. We eat lunch together every day with ingredients from our garden, and they also stocked my fridge with lots of things and ask me everyday if I'd like for them to buy something else. I have an entire flat all to myself with high-speed WiFi and hot water in the shower. It's a pretty sweet deal for helping out in the garden from 9-2! I've even picked up some German.
My house
working on a new chicken fence
picking some beans
A frequent bedroom visitor
I learned to make jam
Transplanting lettuce sprouts
So that's my great experience staying in Germany for absolutely no money besides the bus ticket I needed to get here! I've heard of other similar organizations you can use too like WOOF and HelpX, but I chose Workaway because I preferred their website interface best, and now I can say from personal experience that it's a great tool for finding projects abroad!
Have fun out there!