So many costs to consider, here's just a few thoughts.
you say stealthy, so i assume we are talking about a closet or suchlike small area. here's where i would start:
1) Lights: buy at least two dual-tube 48inch florescent fixtures (bout 15$ each at home depot) and for each fixture, 1 OTTlight tube, and one warm white tube. hang them on chains so you can adjust their height as needed, and 2 electric timers
2) 1" rockwool cubes (12 cubes for 2$) 2" net pots (like a buck for 6) 1 lb bag of loose pearlite (dirt cheap at any garden center, little white pebbles like rice crispies) 3 quart sized spray bottles, stainless or plastic measuring spoon set, and a sharpie.
3) 5gallon buckets. get at least 3, then paint the OUTSIDE of the buckets dark brown (not black) with ordinary exterior housepaint. this works best to make buckets light proof but you can still see inside for cleaning, and root examination, cuz the inside is still white
4) a 2 outlet aquarium pump designed for a 30-40 gallon aquarium (about 15$ at petco) 20 feet of air tube (5$) 2 air stones (2$ each) 1 pint hydrogen peroxide (5$ at the drug store) and an oscillating fan.
5) nutrients. too many choices. i like fox farms (Grow Big 20$ a quart, Big Bloom 15$ a quart and youll use 1 teaspoon a week at most per bucket) and a little bottle of rooting compound (10$)
6) 2 surge protectors (safety first!) and a few extra lamps (ones with the big spring clip are groovy)
Remember!!!!
electrical connections, fans surge protectors, sockets lamps air pumps etc all must be kept HIGHER than any water source
my personal growspace is a garden shed, with 1 4foot fluorescent using OTTlights (full visible spectrum lamps) and warm white (extra reds), and a few clip up CFL OTTlights for side lighting and help with the shady under growth operating 12 hours a day, and an oscillating fan and bathroom type vent fan running 24/7. 4 5gallon bubblebuckets on a 60gallon aquarium pump, using fox farms nutrients 1/4 tsp grow big 1/4 tsp big bloom, and 1/2 tsp of hydrogen peroxide in 4 gallons water. its a simple and cheap way to grow for personal use. total electrical usage: 200 watts/ day averaged over 24 hours.
i change my water in my buckets every week, so i dont have to worry about PH testing, or salt buildup and whatnot. cloning/mother plants live in my closet under an OTTLight with simple spraying of mild nutrient solution with a drop of hydrogen peroxide per quart in my sprayer
total cost was under 200 bucks to get started, and costs very little over time.
