Making seitan from scratch is super cheap! Just buy vital wheat gluten in bulk at a food coop or whole foods and experiment with it. It may take a while to get it how you'll like it, but once you do you can do so much with it! Also t.v.p is cheap and you can make burgers and chili and things like that. I've been vegan for several years now and it seems like making things from scratch is the cheapest way to go, that and making lots of stuff at once and freezing it.
you can make tofu cheaply too, a bit of work, but it's better fresh you can get a lot of materials for fermenting and such at: http://www.gemcultures.com/
and what have i been eating a lot of lately? rice w/ beans, steamed carrots [unless there's free broccoli in the day old boxes outside the food bank], home-made tahini maybe 75 cents a bowl, filling and nutritious
i've worked for lawyers and bankers and insurance companies and advertising agencies and i'd rather eat garbage
right now eating couscous with chickpeas, bell pepper, tomato, cucumber the couscous is expensive, a half-cup [uncooked] is about 47 cents the chickpeas cost about 8 cents the 1/2 tomato 11 cents, the 1/6 bell pepper 11 cents, the cuke was free covered in tahini sauce, hard to say, 10-20 cents? under a buck, tasty, nutritious
Totally just tried an adaption of this, with home-cooked beans and less curry. Yomnomnomnom! Even my omnivore hubby liked it! And the way I did it made enough for 3-4 days of yummy!