I discovered vegan maultaschen (dumplings, basically), which have the exact proportion of macronutrients and fiber that I need in my diet at large, and which can be eaten raw, fried, or in broth. They also cost €2.25 for /~600 calories worth, so very cheap for prepared food, but not really that cheap in the end.
Apparently black beans and rice are excelent and really popular in brazil.
Best part is that you can make huge amounts and freeze it, so you don't even have to cook often.
Preferrably add something else to add some more variety to it.