Hi Caveman,
I was a volunteer and its a very rewarding job in a number of ways, meeting new people, making new friends, learning new skills, its also a massive star on a cv for future jobs, as well as raising money for a good cause, I am now a manager at the shop where I was volunteering and we pay travelling expenses for our volunteers if they need it to get to us.
All I can say is go for it and if you dont like it in one shop go to another, its surprising how different each one is.
Good luck