Do you know how many varieties of the cheapest uncooked rice 🍚 of quality there are extant? Definitely more than 1 variant. And if you are not a rice bin that eats that much, 5-kilogram plastic sacks are more value for money than 10 kilos in over-bull, or 2.5 luxuries of paying more for less. Don't get started on costly premiums of really red raw rice, or truly long grains of more expensive basmati. Not when you are a poor diabetic needing low GI (glycemic index).
Likewise, there are galores of cheap without being cheapskate. Biscuits, breads, and cakes made of white flour and sugar and salt and oil. You of course cannot afford boutique bakes and authentic country loaves, being pathetically poor and all. But you can afford non-local mass produce, coming in mostly daily from Malaysia especially, since we exploit their lower-cost labour. This also can cover starches like instant noodles, eschewing the local brand long of solid pedigree, for the relatively cheaper Indonesian ones that will have to do, to stave off hunger.
Vegetables are good for the budget, right? Of course not! When they are organically grown with guarantee, imported from respectable countries, and not further modified other than by heavy breeding. Hydroponically farmed on our main island farms? Support local produce! If you have the money. Again, the cop-out, small bundles from next door, except those that have established repute - ahem - pricing.
And for now, meats and proteins. Be tacky - use the cheapest decent frozen slabs of meats, and thawed fish to clear by cooking on same day (of you can even get under $10 a kg, or $4 a whole). Otherwise, establish not with known tofu products but house brands, and not Western grown portobello mushrooms but toss-in bunashimeji.
You have been warned. Good variety does not mean burning holes in your money pockets.