It could cost you 150$ - 450$ depends where you live, how you wanna do it and so on. Smell didn't ever leak out of my apartment. ALTHOUGH I always cook, have a good quite vac. and burn candles and incense constantly . Anythings possible brotha. Also, depending the size of your closet, you could get a quarter of reggiebush on your first grow if you don't know what you're doing and have 0 help... OR you could find some helpful and awesome people on this website that will show you how it's done... and end up with a QP, HP or even a few Ps if you're lucky. I wouldn't be were I was today without rollitup (FYI). PM me if you need help.
PS, I use CFLs as well cost is cheap, elec. is cheap and I built my own wooden box with about 10 computer fans wiring them to phone chargers on timers, even the lights on timers. Make sure it's safe when you go ahead with everything. Tents are great too. I ran about 200watts