Sticky tofu is hands down my favorite. Something like this: https://veganonboard.com/sticky-lemon-tofu/

Soy Curls is honestly my favorite 'meat replacement' (though, I'm not too hot on 'replacing meat'). They work for doing things like mongolian beef, or just lightly frying after marinading for 'chicken strips' to top salads or sandwiches. https://thevietvegan.com/vegan-mongolian-beef/

Soups are of course, pretty easy. I like Lentil Chilli, heavy on the seasonings and beans aside from lentils. Minestrone or lemon orzo are both also great. Thai curry or pho are both more work imo, but amazing (though, both broth bases can often have chicken or shrimp in them).

Burgers, and while impossible meat et. al. are fine I guess, they're a bit pricey. I honestly prefer a good chipotle black bean burger over them 9/10 times. They're pretty cheap to buy, but also not very hard to make, with most of the ingredients being cheap.

I personally like seitan, but I know quite a few other vegetarians don't, so it might be divisive. BUT, in terms of cheap protein, its damn near rock bottom in price. It is some work to make stuff out of it from scratch, but 'indian mock duck' is usually seitan, and can be bought from indian stores if you just want to try it. But seitan works to replace burgers, chicken tenders, steaks, sausage, etc. Tons of recipes out there.