The chances are rising that I will make it to Mythodea. In this case I would be able to support the "long distance" visitors of the Grand Expedition by providing access to a fireplace. As far as I am concerned it is not too much differnece between cooking for one person and cooking for a small group. Only thing that needs sorting out is sharing the expense of purchasing supplies.

One tip:

If one crazy night you blindly stumble into a camp of half nekkid barbarians DO NOT drink the strange, sweet smelling, clear fluid someone's uncle fermented in their barn!

-Guy with a headache

Did you know that the bigger shops (weapons, amoury) accept credit cards? Very nice or terrible, depending your point of view.
Considering food: Some very tasty snacks are offered in the city. They range from ~2€ (crepes; tasty pastries) over 3,5€ (potato wedges with super dip o 1/2 grilled chicken) to 5€ (some kind of hemp kebap). You'll always end of buying more of this stuff than you expected, especially if you haven't yet tasted everything and everyone is advertising different stuff^^
Good news: Free drinking water is available and the best in the heat we'll hopefully suffer.

Food is good at the vendors, but it does not beat the atmosphere of a good camp fire. My idea and advice is use the vendors during the day so you have time to take part of the action. In the evening you can enjoy the camp atmosphere by a BBQ or other self prepared foods.
And yes, many people bring many things along that they find great or worth the occasion, a certain caution may be healthy.