Reddit mentions of Painless Vegan Slow Cooker Recipes For Lazy People: 50 Simple Vegan Cooker Recipes Even Your Lazy Azz Can Cook

As others have mentioned, most prepared foods are sadly going to be cost-prohibitive. But here are some suggestions on very low preparation meals, including some lower cost packaged things. Hopefully it will be applicable to your situation.

If you have or can track down a slow cooker (I see them all the time at thrift stores, and you can find them new for under $20) you may find this book useful. All the prep times are short, and then the slow cooker does its thing for a few hours. It looks like most of the recipes make 4-8 servings of food, so you could go several days without cooking.

Some other quick and easy things are hummus and veggie sandwiches, Boca burgers (most, but not all, are vegan), oatmeal (add your own flavors), salads, these microwave rice packets (I like to serve them over some greens with some kind of veggie protein and maybe some dressing or sauce).

One thing you should not skip is a B12 supplement. Depending on how much B12 your body has stored up it may not be a problem immediately, but once it's depleted the effects are serious and irreversible. Deva makes a good line of vegan vitamins.