You don’t have to have a big yard to grow some of your food and herbs. Pots on the porch or balcony will do fine for parsley, oregano, onions, all those relatively small plants.
If you do have room for a full garden, there are ways to do it less expensively. Maybe there’s a gardeners’ group in your area where people trade their extra seeds, and you won’t have to buy so many.
The frugal gardener knows that last year’s seeds are still good this year if they have been stored in an airtight container in the refrigerator. Indeed, mine were just in the cupboard, and they stayed good until the next year.
To test them just before planting time, lay ten seeds in between two paper towels and keep them moist. If at least seven of the ten sprout, the seeds are good. In 2013, I planted 2012’s onion seeds and they grew nicely.
You can make compost in a covered five gallon bucket. I’ve done it. Start with a layer of dirt, such as topsoil or garden dirt. Add a layer of kitchen scraps, stir it into the dirt and get the whole thing wet. Stir it every day and keep it damp but not soggy. Add more scraps and more dirt as the scraps become available. Stop adding scraps while there’s still room to stir the compost. You do have to keep stirring it daily even once it’s full. Over time, the scraps will break down into nutritious compost. You can use raw vegetable peelings, coffee grounds, crushed and crumbled eggshells, and dried grass clippings and leaves. Don’t use bones, meat, grease, or cooked foods.