I had no issues taking aspirin alone for a long time. Only symptom after absurd usage (like 3g/day) was my skin got cut easily. Of course this isn't taking into account the unforeseen consequences, but the point stands that it depends on your constitution. If you're a big guy (for you) like me then you'll be fine, but less blockheaded individuals are prolly more sensitive to downsides.
The prior recommendations to eat ground veggies (carrots, onions, potatoes, etc) is good. Produce is generally pretty cheap, or at least you need to do homework on what the cheapest peaty (or peat compatible) items in your area are and prioritize them. My main concern is getting a good source of carbs - is fruit consumption enough? If not, then try looking at frozen berries, or refined sugar if you're willing (though that may be risky long term).
I want to jeer at CO3 for recommending mentioning shoplifting but I am a resourceful man myself and would regularly steal utilize free food from from the work break room. I'm pretty sure I'm the reason they stopped supplying it with oatmeal packets (saved my coworkers from a life of starchceldom btw). Now I just make use of the free oranges and pears. I would suggest similar resourcefulness in your case. Indulge in the packets of sugar at restaurants. Mooch off of your friends. Combine multiple small snacks into a meal. etc
I would recommend vitamin E to cope with any PUFA you inevitably consume with a budget diet but the generic off-brand alpha-tocopheryl prolly isn't gonna do much. Stick to the aspirin and the coconut oil as tactical deployment.
Consider also your physical needs. If 1) your life circumstances are not physically demanding, and 2) you don't really care about being a beefy haidutian lifter then you can maybe skimp out on fat and protein. Or at least I eat a lot more fat than I should and get away with it because of constant physical laboring. But there are cheeky ways of getting these macros, if you calculate the costs of the cheapest sources - eggs, creams, gelatin, etc. Maybe there's a clever way of integrating some new cheap food item to meet these demands.
You can also simply fortify existing meals with good food items. This is what I do with cheap meals, like adding sour cream and coconut oil to box mac and cheese for extra fat content. If all your food is homemade (which it should be, poor people who only eat premade food deserve it) it should be possible to customize it a bit in your favor.
Lastly, find some way to do all of this in a way that is stimulating rather than taxing. When I cut costs and do budgeting work I like to pretend I'm some guru doing dramatic calculations, like I'm playing a survival game and I'm solving exactly how to manage my limited resources. It helps to keep things fun and exciting rather than boring and stressful, which will indeed cause problems as this state persists.