The best aspect of couchsurfing isn’t financial, but social. Free accommodation does help to stretch the travelling budget, but what’s far more valuable, especially for a solo traveller, is the way it makes it easy to meet people in the areas you’re visiting, see their homes, meet their friends and family, and get a feel for their lives. There’s also the bonus of getting their advice on the best places to visit.
Couchsurfing caters specifically to this by allowing people to arrange to meet just for coffee, or food, or for sightseeing, even if they’re not surfing/hosting together.