I think in the US, about $1,000 per month is a pretty good basis for camping comfortably. A decent hotel once a week is nice, so add that on top of the $1,000 depending on what level of hotel you desire. You can stay on a cheap motel for $50 or a decent hotel for $80-100 depending on where you are. You can definitely do it on less than $1,000/month with warm showers and free camping if you’re in an area to do that and if you don’t mind keeping things really cheap. I like to eat in a restaurant some and get a bomber or cheap bottle of wine a lot of evenings, so for me the $1,000 is the pricepoint I’m in. If you want to do hotels and restaurants all the time, the sky is the limit on that budget. In Central and South America you can eat more cheaply and free camping was no problem in the areas I’ve been. Southeast Asia is dirt cheap for cooked meals and lodging. You can get a full meal’s worth of street food for a dollar or two, and a place to stay for $10. I haven’t bike toured in Europe, but from what I saw visiting and what I’ve read, it’s more expensive that the US.