Multivitamin ~10$
  1 gross eggs ~20
  30 cans refried beans ~20
  ~100 small tortillas ~7
  5 lbs rice ~5
  3 lbs sour cream ~9
  salt ~.7
  pepper ~1
  garlic ~2
  10 lbs potatoes ~10

spend the remaining ~3/day on whatever you feel like. suggestions include: pasta and sauce at ~1 a meal. whole fat chocolate milk at about ~2 a day. a pint of olive oil a day. a case of ramen a day. a pint of ben and jerry's (there's 2000 kcal by itself).

Prices sourced from an H.E.B. supermarket in Austin Tx. Oh, also, I've been living on less than 3$ of food a day for the last year, so this isn't exactly theoretical. 230 per person per month would the height of luxury for me.