I think you're on the right track. It's tough to beat a 3x3 tent with HPS and air cooled hood. (Apollo makes a decent tent available on amazon for $100).... HPS is the best option in my opinion, unless you have a bundle of cash for COB LED's.. 400 watts does an ok job in a 3x3, but I wish I had a 600w ballast in my 3x3 because coverage would be better. Maybe a 400w plus a bit of fluorescent on the sides during peak budding would be best.
You will need around 150-200 CFM exhaust fan.. No big deal. go for the 6" fan so it connects easily to most hoods. Make sure to get a good filter (phresh is good) and a fan speed controller ($25)
2 gallon pots might be a bit small but you could get six plants in there.... four 3 gallon pots with plants 2-3 ft tall works well in a 3x3.
Don't forget we have a 6 plant "limit" in most areas. If it weren't for the limit I think I'd so SOG and just pack the tent with clones.
Check out craigslist for grow equipment. In Cali equipment is virtually free. It's always some guy that moved in with his girlfriend and is forced to sell his beloved setup for pennies on the dollar
This is 4 plants in 3 gallon pots in a 3x3..
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