Maybe this isn't proper shopping but $18.50 for four veggie burgers, buns, and danish seems like a lot

I get a sack of rice, a couple avocados, dry beans, frozen broccoli and corn, lime or two, bunch of spices if you don't already have. Whatever Mexican spices recipe online but definitely get smoked paprika it's straight up drugs. This will cost more than the burger set in the picture but it makes more meals.

Instant pot rice, instant pot seasoned beans with a second inner pot, 1/8 of tall wide mouth mason jar each of rice and beans, arbitrary amount of broc corn and cubed avocado leaving about 1/8 of jar as air, tablespoon or so of lime juice. Cool the jars and freeze once cool. I use plastic lid rings with silicone insert since the metal ones get rusty when used like this. I'll prep like 40 of these in one session but that's definitely using a bigger budget so I don't have to do it as often.

My recommended rice is long grain brown with about 1/16 to 1/8 of the amount cooked being wild rice mixed in. They both take the same amount of time to cook when mixed, but it's a decent amount longer than white rice. I usually put an arbitrary splash of sake or gin in the water for cooking the rice but it's largely a habit from copying grandpa.

I take a frozen jar to work with me in a lunch bag and it doubles as an ice pack for whatever else I want in there. I aim for it to be thawed enough to shake it and mix it before microwaving. For at home I thaw it in the fridge the day before. When I didn't have a microwave I just steamed the whole jar in the instant pot.

Jars and instant pot + accessories were all things I waited for sales on. It can be done without instant pot but it's probably the safest way I can think of to cook things and fuck off without worrying about it burning the house down. Jars are merely the cheapest I could find in decent quantity and dishwasher safe.

This is probably the cheapest with highest output volume food option I batch prep. I also do things like potato leek and/or squash soup, or potato cheese and soy bacon soup (I'm not actually vegetarian or vegan but it's a real pain cooking all the bacon needed and cutting meat is tiresome), and some other stuff that has been hit or miss that I only tried once. I keep them all in a chest freezer and I take out whatever I feel like eating as an easy microwave meal, unless I'm running low and need to reserve them for work lunches.