A 3x3 footprint is good for a DWC - 1 plant in a 5gal bucket, if you've grown inside then you have the right lights and temperature controls. What you want to make sure to get is a water pump (I would say about 250+ gph, prolly about $12-20 at your friendly neighborhood hydro store). The key to DWC is water aeration, so get an air pump and an air stone (around 15-20 dollars at walmart total - pump, stone, tubing)
Your list should look like:
5gal Bucket + Plant pot Lid - $10
Water pump + Irrigation Hub - $30
Air Pump + Stone + Tubing - $20
Also media ie. rockwool, hydroton, ect. -- Both these types of media are great for an ebb & flow system, but for a recirculatingDWC system they have a chance to cause nutrient lockout (prevented by flushing, not fully prevented however)
If you end up wanting to use your rubbermaid (I'm assuming its a 18 gal type - for multiple plants use a bigger water pump 400-600gph about $30) make sure to not veg the plants for more than a few weeks, especially if youre putting more than 2 in that space. Tools to put holes in the top of the rubbermaid are expensive where I live, up to $40 per drill bit, but you eventually save on buying more than 1 - 5 gal bucket for more than 1 plant.
What you definitely want to look into getting is a pH testing kit, and a more effecient way of measuring out nutrients (trust me about 2-3 weeks into your grow, measuring out nutes w/ tea/tablespoons is gonna get old fast, I suggest a syringe looking plunger thing).
Eventually you'll want to invest in a pH/ppm Electronic Testing Pen, about $200-250 (They are the shit.). But that'll be later when you have the money.
Things to look for in a DWC system:
Make sure your water isn't too hot or too cold, about 60-65f is good, if it's anything besides that make sure you have extra air pumping into the water (Don't be afraid of getting a double pump and 2 air stones, the more air the better).
Make sure the pH of the water is between 5.5 and 6.5 (You're gonna want to get a pH test kit from a hydro store, the pool tester kits don't measure pH with much accuracy)
Make sure the plants have water (This is especially important when they get bigger, 1 plant in a 5 gallon bucket w/ 1 month of veg is prolly gonna drink 1-2gals of water a day, meaning only 2 days till the well is dry).
Also make sure you have enough room to flower when decide to flower, (in a 7 foot tent, the plants start at the top of the bucket which is about 14-18in, let them grow to a max of about 2.5-3ft - from the ground - and then start flowering -- this growth will take about a month, maybe less)
Your feeding schedule should look like:
1st wk - 50% Veg solution
2nd wk - 75% Veg
3rd wk - 100% Veg
4th wk - 100% (4 days into wk 4 - drain and fill with clean NO nutrient water, make sure the next 3 days are all clean water too -- Called flushing)
5th wk - 50% Flower
6th wk - 75% Flower
7th wk - 100% Flower Solution
continue w/ 100% till the end
3 days before the end you'll want to drain and fill the res w/ fresh clean water, and a sweetener (you can find info about these all over RIU) - some people vote against flushing, but I think it helps w/ the flavor.
If you're not vegging for a month, step up the feeding schedule by a week or 2, (but don't ever start off young plants at 100% its a sure way to kill them)
Care of hydro plants is similar to soil plants, growth is quick in hydro vs soil, about 2-3 times as fast (3x3 room w/ soil plants, veg would be about 2-3 months. With 5gal dwc about 1-1.5) so they react quicker, if you should mess up the nutes and hurt your ladies(they will show), flush for a day then start again w/ less nutes)
Don't use the Lucas formula (trust me, it's just a fad.) because if something goes wrong with your nutrient mix you're going to have to change it (and then it doesn't become the lucas formula anymore). Look for good nutrients that are made for a recirculating system (nutrients is mostly personal preference, some swear that different ones give you different yields - There is really no way to test this)
You can prolly piece a DWC system together for the cost of an 1/8th, shop around for good deals and stuff.
-- Most of this information is just hydroponic growing stuff, I'm assuming that you've grown indoors under lights before and know the proper way to control your grow room --
-Vel