Please op, consider that your time and efforts put into raising, feeding, watering, cleaning pens, etc. is part of your costs per egg. The more time you must spend caring for your chickens' needs the more expensive your eggs must be to recoup your costs. If your eggs are more expensive than store-bought, why would folks want to by them? By giving your chickens an enclosed yard to spend the majority of their day the time you will spend cleaning their poop is lessened. The more weeds, grasses, bugs, veggie scraps they eat to round out their diet, the less you will need to spend on chicken feed (the price of which continues to rise. The less stressed a chicken is the fewer health problems they will develop. If making money off egg sales is your goal you have to consider what your time is worth and add it to your other start-up expenses. On paper, the sort of business you are considering rarely makes anything close to a profit and usually works at a loss every year.
Factory chickens, confined to the size of cage you are considering have a very short life expectancy when compared to unconfined chickens. You will need to slaughter your hens after two years due to fewer eggs showing up (and the meat will be not good for much other than frying) and then buy new chicks and start the cycle all over again.
If I was in your shoes I'd spend my first year building the biggest and best coop and yard I could (wood pallets are found free all over the country for materials). Paint it pretty for your mother. If you need help building it right, ask for help from someone and offer to pay them with free eggs for a month once the hens are laying. I'd build my own feeders, waterers, nest boxes, etc. and there are many, many photos on this BYC site to look over and copy. I'd read, absolutely everything I could, every single article, about all the aspects of raising chickens I could find. I'd find as many folks who also raise chickens (small scale) in your immediate area to pick their brains about weather concerns, breeds that do best in your area, local predators, shows, egg prices, where they get their feed, local vets that care for chickens...there is so much to learn! Put together a small medical emergency kit. Get your brooder ready and THEN order your chicks.
Don't limit your dreams by thinking small cages are the cheapest way to go...I think you'll find they won't be when you consider the problems inherent with that type of husbandry. The last thing to consider...chicken math! 24 hens turns into 30 hens mighty fast!
Best of luck and enjoy learning about chickens