You can build a 4 site DWC (deep water culture) hydroponic setup for about $75 very easily. There are many plans for this, but a quick list is

20 gallon rubbermaid tub (dark so there is no light entering)
4 output airpump (or 1 dual output and 1 single output)
4-5 airstones
4 6" netpots with around 4 litres of hydroton (clay balls)
General Hydroponics Flora Nova Grow and Bloom (1 part systems, good results, very simple) nutrients

And wahla. With a 400 watt light, you can produce 4 ounces in less then 3 months (including curing) if you start from clone. Ive been using this system and I flowered when the plants were about 2 weeks old (10" tall?). They are now 3.5 feet tall and still growing. You can also make the 20 gallon tub a 2 plant site instead of 4, which I prefer. A pH pen ($100) and a TDS/EC pen ($80) is a great upgrade, because it enables you to fully take advantage of the hydroponic situation, getting the exact PPM and pH you need for plants to flourish.