I like to take a package of nissan brand Oriental ramen (the ones that usually go for 10/$1), add the flavour packet to the boiling water, toss in some red chili flakes and whatever random veggies that look good. Make the ramen according to package directions, and add veggies after draining most of the water (so it will be a sort of noodle soup instead of a bowl of pasta and veggies). Good stuff and it's cheap to make.
Bean burritos are also wonderful. The low-fat variety of Safeway brand refried beans are just water, beans and salt and they go fabbo in a whole wheat tortilla (or a flour one if WW is hard to find). I toss in a bit of ceyanne pepper and garlic while the beans are warming up and sometimes, I'll put in mushrooms, zucchini or red bell peppers into the same pan so everything heats together. They're extra-nice with some quinoa in place of the rice and guacamole kicks it up a veg*n notch. They don't even need cheese. Just a fork because sometimes, they're a tad messy.
Nachos are super-yum. Refried beans with just a touch of olive oil (to thin them down a tad) spread on top of tortilla chips. Raw spinach leaves, olives, onions, guacamole, tomatoes and some yummer-ific salsa overtop makes a great meal and it's filling, too.
Tacos are another "cheap and good" vegetarian food. Some use TVP in place of the ground beef but I prefer just good ol' refried beans and whatever taco fixins you like. I also like a good fried taco, so I'll make a "stuffing" out of sweet potato, mushrooms, onions, and red peppers (or whatever you have on hand that looks good) stuff them in a tortilla and fry them. If you don't want to fry them, then the pre-made shells are a good way of going and everything goes great in a taco. Guac and salsa overtop makes it all deeeee-vine!
Spaghetti with a nice vegan pasta sauce (Hunt's brand is vegan if you don't get anything that has meat and/or cheese in it) is delish, too. I like to toss some random veggies in my spaghetti sauce while the pasta's cooking so everything can heat together. I've also found that brussel sprouts in the sauce not only look like meatballs; they also mimic the texture of very lean meat. Mostly, though I'll toss in some veggies and have done. Pasta is also good with just stewed tomatoes if you want "quicker than quick" food and for variety, I like to do stewed tomatoes, olives, sliced beets and onions with veggie pasta (the stuff that comes in the different colours).
Bowls, bowls, bowls. Quinoa bowls or rice bowls with assorted veggies make for easy, cheap, "quick to put together" dining. Any veggie goes great with quinoa or rice and for extra kick, spice the water in whatever flavourings you like before adding your grain or you can use veggie stock for your base and season it from there (or not).