Hi Serenity. You've gotten so many good ideas! Here's a couple more ideas. My husband loves to get stuff cheap. He comparison shops. WalMart is good for cheese & low-cost yogurt & lots of other stuff. The Dollar Tree and some of the other really cheap stores have food, including soymlk, with great prices. I think somebody already mentioned coupons and weekly sales.
I'm losing weight using "The Engine 2 Diet" by Rip Esselstyn. He's a firefighter and a lot of firefighters, who eat very well, lost loads of weight and cholesterol on his diet. It is really delicious and I don't go hungry. He has 2 websites: The Engine 2 Diet
and Engine2.org > HOME
He gives you 28 days of meals for his diet. He says, "If you don't feel like generating your own grocery lists, then let us do the work for you." Another excellent website is Fatfree Vegan Recipes
Its recipes and the name speaks for itself.
When I was in my 20's, I had a couple of times when I had to go really cheap on food. I empathize with you. Good luck!