Cheerful meat-eater here. I think that, if you got your protein through legumes, that would be even cheaper than eggs. It would probably mean rearchitecting your food in general rather than using drop-in replacements.

One website says that the cheapest eggs on its list (Costco) are 70 grams of protein per dollar, while the cheapest beans (pinto) are 80 grams per dollar, and lentils are 116 grams per dollar. Hmm, that difference is smaller than I expected. https://efficiencyiseverything.com/calorie-per-dollar-list/