I still buy the vast majority of my own food, but:
I've been eating the same $0.99 bell pepper going on three years now.
A $3 packet of jalapeno seeds has made a year's worth of taco tuesdays.
I'll never buy Mint again; I couldn't get rid of my patch of peppermint if I wanted to.
I can grow much better tomatoes than what you'll find at the local mega mart.
A $3 packet of okra seeds will thicken a year's worth of gumbo.
My little vegetable garden, which is smaller than my living room, yields somewhere in the neighborhood of 100 pounds of produce every year.