My latest 4500 mile X-C tour cost about $25 per day, from $10 to 15 for food and the rest for camping, lodging, maintenance, etc. I mostly free-camped--as mentioned above, that's surprisingly easy. Many days I had a bag of groceries from the day before, camped for free, and spent nothing. Then maybe I'd splurge on a buffet and motel the next day. I was pleased at my spending. I'd heard $30 to $50 is most common.

I just had a warmshowers.com guest who is spending $5 per day for the last three years So much cheaper is definitely possible. But he says he has been known to salvage venison steaks from roadkill....