Some good advice and perspectives have already been offered in the previous comments.

I do not consider food costs to be part of the trip cost since I would be spending almost as much at home anyway. My additional trip reserves cover transportation to and from the starting and ending points when needed; R&R hostel or motel costs if needed; spare parts and any mechanical or medical breakdown costs.

I cook very basic food in camp or at home most of the time rather than eat at restaurants. Brown rice or quinoa, steamed vegetables, beans or lentils and chicken or fish and little or no processed or prepared food reduces costs considerably. It only requires a little more time buying and preparing the food and additional fuel expense. I have managed to survive well on tours for many decades eating this way. On many tours I find that trip costs for food was less than those at home.

Given enough resources you can spend as much as you want on a tour. I prefer to use money carefully since money not spent on one tour can fund the next one. In this case, less is more.