Personally, after I add up all the bills, often times it averages out to about $40 to $50 a day.Out of curiosity is that counting only daily expenses or are you counting airfare, shipping the bike, maps, and other stuff bought pre or post tour? Personally I can't see myself spending that much, but some spend more.
I think if you count buying the bike, racks, and panniers and also count airfare and other pre or post tour expenses we still came in at good bit less than that on our Trans America.
On my spring tour I didn't cook, ate restaurant food most of the time, and stayed in a motel half the time. Not counting air and train fare I think it came in at a bit under $30 a day. That was in Kansas where motels are generally real cheap. Being a cheapskate, I think that is about the max I am likely to spend.
My calculations are for daily expenditures for a solo rider. I'm not an extravagant traveller, I free camp once in a while, but when I'm cold and wet, I'm well off enough to buy my way out of a miserable night
To spend $20-$25 on food alone ($5 in breakfast, $7-10 on lunch and dinner each) and budget the same for lodging (sometimes free, sometimes $10 for camping, sometimes $50 to $60 on a motel, which averages out) is about my norm. I find realistically budgeting $1200 to $1500 for a month of travel is better than scrimping to the point of not enjoying or coming home broke. I think I spent way more than that when I rode up to Alaska.
On your spring tour you say you spent under $30 a day while staying in motels half the time. Are motels in Kansas really less than $30?
On free camping, personally, I am less inclined to do it outside of my home country (Canada). I am just more comfortable knowing I have rights as a citizen when I am doing it. I find people are increasingly protective of private property, especially in scenic areas where most of the real estate have claims.
I guess my primary reasons for going on a bike tour are it's a great way of travelling and seeing the world, it's a beautiful way to experience different cultures and taste new food, and it keeps me healthy. Well worth twice the price I pay. As for my exercises in frugality, well, I do them mostly when I'm home