@Rosalind41
Maybe $30ish/month?
We book mostly to families or groups of 4-5. We have about 10-20 booking a month.
I leave a dozen eggs, half of a stick of butter, large bag of English muffins and some frozen food in the freezer (hot pockets/burritos/egg rolls). I might leave beer if it's leftover from a previous guest or if it's something I bought myself and just didn't like. These things go slowly but are often mentioned in reviews even when people don't eat them. $12 lasts about 3 months
I also leave a few small packages of mixed nuts or packaged cookies (bought in bulk and stored in a locked closet at the AirBnB). I might buy mini yogurts for them if they are on deep sale. If I have fruit at home, I will leave them some from my own fridge if they have children in the group but I don't go to the store just for this. These things go more quickly. $30 total - lasts 1 month