Two things:
1) Is it just me, or has Faye appeared thinner in the last few strips? Not sure if it's intentional per the storyline or just a slight shift in art style.
2) Eating cheap is fairly easy, it just takes willpower.
- Bulk dried goods (beans, rice, and noodles) will make up the majority of your diet; there's a reason they're a staple for most of the world. Don't buy a 1lb sack of rice, buy a 10lb sack of rice - bulk savings are real. Learn to cook them, learn to use spices.
- Store brand EVERYTHING.
- Family sized canned vegetables are *cheap*, and really aren't that much different from fresh in terms of nutritional value (spices will cover up that metallic taste)
- Buy uncooked whole chickens. Pound for pound they're the cheapest meat you can buy, and can be prepared to provide meat, hearty stocks, and fat.
- A multivitamin (again, store brand, because you're generally paying extra just for a name when you buy name brand) fills in the gaps.
- Basically just buy the least processed form of food you can in the largest quantity available and learn to cook.