It is possible to do a 60 day tour of the S.T. for the amount of money you mentioned, say $20.00 or $25.00 a day. Another person and I did it for about $1600.00 total for the two of us, and that meant free camping the great majority of the time, or staying somewhere free of charge. Motels up the ante a bit, and can up is very much if you make a habit of it. On some days I would spend $30.00, and on other days $8.00. Within certain limits you can spend about as much or as little as you want on such a journey.
As for myself, I like to drink ice coffee and hot coffee, and a Starbucks is kind of hard to pass up. I add on costs, but what to heck, if I cannot enjoy it, why do it? And I do use motels occasionally. I rented a room in Van Horn, Texas one winter and planned to stay a couple of days, and then cycle on through El Paso. A winter storm came along and covered the ground and roadways with ice and snow. It snowed continually. I ended up keeping the motel room for about six days instead of two. You have to deal with exigencies sometimes.