I avoid shopping in the specialty health food stores and shop the local ethnic supermarket sales instead. I stay away from Whole Foods- which many people call Whole Paycheck. I buy nuts and dry beans in bulk at an Indian supermarket, and I concentrate on the cheapest nuts. I would eat more tofu, but I might have endometriosis, so I'm moderating my use of it for a while. One local Chinese supermarket sells tofu in an open bin for only 25 cents a block. I'm learning what veggies are cheaper than others and building the core of my diet around them. We avoid buying organic (we avoid the "dirty dozen" list and find substitutes that are just as colorful- for example, instead of organic red bell peppers for a touch of red, I often use home-roasted tomatoes. Instead of organic carrots, I julienne sweet potatoes, etc. This only works when I'm just cooking from inspiration, not following a recipe carefully)
Experts on plant-based eating say that there is usually a transitional time period in which people spend a bit more as they experiment with new foods, but over the long run you can save a lot as you learn to make foods from scratch, find better sources, get to know other vegetarians, spend less on health care, etc.
I am taking a B-12 supplement to make sure I get the nutrition I need, but it's dirt cheap from Puritan's Pride when bought in bulk.
I only started the plant-based diet in February of 2011 so I'm a bit of a newbie. I figured if Bill Clinton (with his love for fried southern cooking) can do it, then I can too! I'm loving it! What keeps me loving it is all the fun recipes online and in library books so I never get bored. I never feel deprived!
The world reveals itself to those who travel on foot. ~ Werner Herzog