This was my reply to her.
NO THEY DON'T (need expensive lumber)!
They require you to think out of the box and to recycle what you have!
I don't know where you live, but if you have any kind of newspaper or other place that gets stuff on pallets, go ask them if you may have the pallets. Take them home, break them apart and use the wood.
Been there, done that and it works just fine! Made square foot gardening blocks and housing for my chickens with them.
Later, after I bought 5 acres and later married, my (now ex) husband worked across the street from a concrete place. He noticed that they had a pile of broken concrete blocks - cinder blocks. The kind that are rectangular, have two flat sides and two open sides, split down the middle so there were two sections in each block. He asked if he could recycle the broken blocks and they said yes. So every evening he would put about 4 blocks in the back of our small truck (don't carry too many. They're heavy and you don't want to damage the truck with too heavy a load.)
I measured out some 4x4' square and set the blocks up so that the holes faced up. That gave me extra planting spaces. I stacked the blocks two high for support. When I had about 6 squares, I called the local "dirt" company and bought some top soil/mushroom compost (from a local mushroom place). (If they don't have any "compost" type dirt, just buy the top soil and find someone with a stable. Then learn how to compost.) A dump truck load cost me $5. I'm positive it would cost more now! But still, even if it's $35, it's worth it. They deliver it and put it in one spot, so pick a spot before they come out. Make sure the truck can access that spot and that you can stand looking at where it's located for a while. Do this AFTER you have your squares built. Also remember a new garden doesn't do as well it's first year.
Why in the world would someone use a BACK HOE to dig up a garden??? Not having any gardening experience, you didn't know any better, but the back hoe operator certainly should have! That's like trying to kill a fly with a cannon ball and did as much damage. People use a roto-tiller to dig up a garden. It only digs down 6-24 INCHES. A shovel works too, just a lot more work.
Let's suppose that there are no brick places, no pallets or other types of "free" wood to build with. Then start asking construction sites if you can haul off their lumber - when they're done with it. lol. If that doesn't work, use your old milk jugs, juice bottles, etc. Cut drain holes in them, add some top soil and then refer to a Square foot book, website, etc. (any intensive gardening site will work.) You can put 1 tomato plant, 2 green pepper or hot pepper plants, 4 small herbs, or about 36 carrots in a one gal. milk jug - if I'm remembering correctly.
Wait until you've got a garden going well before you buy the chickens. (you can go to the feed store in spring and buy a sack of starter feed and they'll give you 6-12 chickens. At least around here they do.) Last time I bought a sack of starter, it cost $7, but that's been several years ago, it's more now. But why should you wait?
If you're having to buy all their food, you're not saving any money. It will cost more in feed than you save with the eggs. Oh, by the way, home grown chicken tastes REALLY different from store bought. Enough that you may not care for the taste. Before you go buying 100 broiler chickens "for meat". Raise, kill and eat one. Make sure you and the rest of the family will EAT the home grown meat. Both because of the taste and because of killing it yourself, you may find rebellion in the ranks. You could also raise rabbits for meat too. But the same thing. Raise and eat one before you go into it wholesale. (After the first time one lay's your arm or stomach open with it's hind feet, you won't have any trouble eating it.)
Also wait until you've got the gardening down before you add another job. Make sure you can put up the food you grow, or it's wasted. A smaller garden to start with is better than a big one that you throw food away or let spoil because you couldn't handle the preserving of it.
For me, Square Foot Gardening has been a blessing. Minimal weeding, watering and care. Nice amount of food. I'm not having to weed and water the spaces where I walk. I don't have to over-plant and then thin to the proper spacing - saves seeds and my time (we homeschool too). (Or fail to thin - who likes to kill all those baby plants, and have a poor crop because they're so over-planted that nothing can grow properly.) Gardening this way requires no special tools - no shovels (unless you're moving dirt into the squares to start with.) no rakes, hoes, hoses, etc. I do mine with a tablespoon, a sharpened pencil (to poke tiny holes), small scissors and a watering can (recycled metal or plastic can that I used a nail and hammer to poke holes into) and seeds. (I've kept mine in the fridge, in zipper bags and they've sprouted for years after the "good" date.)
Remember, the food from the garden helps with the feed bill on the critters. Start now with a "composting" bucket on the counter. Each time you peel veggies/fruits, scrape plates, toss left-overs, etc teach yourself to put them in the "compost" bucket. Lean what can go into the bucket (no meat, fats, and a couple of other things.) Each evening, go dig a spot in your yard or garden and "plant" the bucket contents. Or make a regular compost pile. When I had chickens and rabbits, I used the scraps to feed the animals with. Just make sure you empty the bucket each evening and clean it out. That way you won't encourage bugs or mice. Also, put a lid on it during the day helps too.
I did these thing when I lived in Florida. Now in North GA, I can't have a garden. Well, no. The rules are that I can't dig up the yard. I can plant stuff in my 55gal drums that I had cut in half and filled with topsoil. I can put stuff in containers on my porch. I can dig up the area under the eves, next to the house. See what I mean by outside of the box?
I just wanted you to know that you don't have to do bells and whistles to have your dreams. It only requires thinking outside of the box. Look at what is needed and then at what you can use to substitute with what you have on hand.
Then DO IT. Get the kiddies to help. You're teaching them a life skill as well as the interesting fact that kids tend to "like" and eat what they've planted. Mine would eat stuff out of the garden, raw. I never cared that they had peas and carrots for breakfast. Straight from the bush to their mouths. (I didn't use chemicals on my plants, and was on 5 acres, so there was no chance of contamination from a neighbor.)
Only you can make your dreams come true. But don't sabotage yourself by thinking you need expensive things to work with or a lot of money to start these kinds of projects. The Pioneers didn't have stores to go to, yet they were able to raise gardens and feed their families. You can too. Recycle, reuse, repurpose, thrift store, out of the box thinking will get you where you want to go. Make a game of it. Teach this game to your kids. (I have a 2'x2' box, what kinds of things could we do with this box. I need plant starter pots, what kinds of things could I use to make them. Then make a list of everything you can think of. These are REALLY good exercise for you and them. They will expand your creativity!)