@Reader, As I mentioned above, I am a trained Personal Chef and member of the US Personal Chef Association. But that is not required anywhere in this country to call yourself a Personal Chef. It does give me a good knowledge-base of the field and what can and cannot be done. Some counties/states may require you to have a Food Handler's or Food Managers's Certificate, but those area low cost tests of safe food handling information and skills -- min/max temperatures to store and cook foods, sanitation, best practices in kitchen safety, etc.
I don't budget for food per se. But I do food cost analysis regularly. I know for example that eggs cost me 33 cents currently, a slice of the "good" multigrain bread that I buy for toast is 14 cents, challah bread for French toast is 46 cents a slice, etc. The same for sausage, bacon, fruits and other items I serve. I know how much a serving of each of my menu items costs, and I try to keep that under $2.50 per serving.
Living in Florida, I'm lucky that I can often get different fruits for free from neighbors, friends, etc. Or by "gleaning" -- there are banana trees nearby in a local power company right of way; likewise a starfruit tree, a couple mango, feral orange and grapefruit trees that are "freerange" not in anyone's orchard.