Now in Belgium, a fake chicken meal with 2 fake chicken fillets is <4€

The cheapest chicken fillets at aldi are 6.50 € for 2.

Here real meat has been increasing for years while plant based stays the same. Ground pork is still cheaper though.

The actual chicken fillet is like 1.5x the protein still, but not too bad. My girlfriend is not veggie and I feel financially bad now also when I get meat for her, but she needs very calorie dense foods sometimes because she can't eat a ton.

You might be able to incorporate more lentils and beans. They're dirt-cheap and fill you up similar to meat.

I always get pre-cooked beans, and red lentils are my go-to for lentils, because they cook quickly and don't need pre-soaking for reducing their fartiness.

non-meat stuff to be cheaper

Beans and lentils are dirt cheap and a great source of protein and fiber.