I will assume growing mj where you live is illegal. Ill also assume mom wouldn't approve. Hate to point out the obvious, but
1:
growing even 8 plants take more room than you'd think.
2:
Lets dabble into plant food. Plants use light for food. Lights take electricity. To produce enough weed to be worth the hastle to sell, you would be paying a big enough light bill she's notice it a tad.
3: The damn smell. Iy you'd flowered mj before, you'd know that youre dreaming if you think locking a door will keep it from being a problem. With expensive filter setup, YOUR room may be the only place it stinks. Just don't open the door. also, some nutrients are NOT odor free.
4: noise. Proper ventilation is easy to achieve, hard to get silently. Fans make noise. Even cpu fans can be heard.
5: mess. if you use soil, youre going to make a mess. If you go hydro, you;ll have lots of water to move around.
6: Harvest if your crop is a success, you aint smelled nuthin yet, cut them babies and dry em. Your neighbors will want to come to party!! (w/o adequate filters)
Financially.. Getting a crop going that actually makes money for you means you have to invest in time and equipment. $1500 would be a nice start, but its going to take a while to recover the startup. Also, theres the cost of nutrients and electric and water, and all the other odds and ends you end up buying to perfect your craft. I would highly reccomend you NOT trying to grow MJ to make money.... unless, you treat it as a business, and expect to invest accordingly. If it is illegal where you live, this is a business that could cost you more than money, it can cost you jail time.
Morals : Mom is paying your bills? It would be a folly to do something illegal that she disapproves of.. in her house! I dont know the laws where you are, but could they take her house? My mom was a teacher, theyd took her career. You may have the best intentions, but the judge cares not. Sounds like you are new to growing, so I would say that its presumtious at this point to think you can commercially grow under your conditions. If you feel it may be morally wrong, perhaps it is. Morals are a trait that is individually defined. All morality aside. the logisitcs of it make it a bad idea considering your living status. If you want to grow to make cash, get you a buiding designed for it, and spend some cash. Perhaps YOUR local govt has farming programs or permitting to help?
Hobby : learning to grow can be a fun hobby. Like all hobbies, it will cost you money in the beginning. If you develope a love for growing, you will lose track of the expense. Its a hobby for me, and everytime I think I made proffit..... i buy newer shit. Such is the life of a stoner striving for perfection.
IN summary : Wouldnt do it man. Venture into another money making enterprise. Honestly, selling what someone else grows sounds more feasible. Tho, i dont condone illegal activities..