I don't keep all of these items in stock all at the same time. I shop for bento foods in cycles. Each week I will grab a few things from each list; pantry, fridge and freezer. It takes generally 2 weeks to use up all of one item. So I always have bento items on hand already. When making my grocery list I have a special section on it just for bento foods. I mentally review last week's list and make sure to get different foods on this week's list. There are exceptions, of course. Lettuce, fresh fruit and baby tomatoes I buy every week! And bags of frozen fruit and veggies, peanut butter, nori, etc. last a long time and I only buy them when I'm close to running out.
Pantry:
soy sauce
sesame oil
sesame seeds
soba noodles
spaghetti noodles
chickpeas
black beans
bread
peanut butter
Fridge:
baby corn
baby tomatoes
black olives
lettuce
cheese
tofu
apples
grapes
veg hot dogs
feta
ravioli
carrots
Freezer:
gyoza
chik nuggets
meatballs
onigiri
mango
peaches
blueberries
grapes
steamed buns
broccoli
cauliflower
corn on the cob
corn croquettes
fried tofu
mini pancakes
Decorative:
Provolone cheese (my new fav!)
soy bologna, ham, turkey, etc
nori
cucumber
mamenori
soy pepperoni
sugar sprinkles
icing
Sample Bento Grocery Lists:
Week 1
Lettuce
Apples
Provolone cheese
black olives
baby corn
soy ham
bread
Week 2
Lettuce
baby tomatoes
tofu
chickpeas
carrots
soy turkey
cucumber
Week 3
Lettuce
clementines
mini pancakes
bread
chik nuggets
veg. hot dogs