A good, yet basic grow setup, expect to spend $200-$500, depending on what materials you already have on hand.
A beginner with CFL lights should be able to get 1/4 ounce from each plant minimum. With a budget that allows for LED or MH/HPS lights, you should see at least 1/2 ounce from each plant, but closer to 1 ounce, possibly more, from a beginner, and would need at least 16-32 plants total at that rate. Of course growing high yield strains, and proven strains will help reduce the # of plants needed providing proper care is taken when growing.
It isn't rocket science, but you also have to be observant and have some attention to detail to notice any abnormalities in your leaves, which will be the first indicator of a problem that needs to be fixed. And we have all the charts and pictures needed to figure out the problems.
As a ballpark estimate for all equipment (I'm assuming LED or MH/HPS setup @400-600watts), seeds, growing medium (or hydro), nutrients, fans, filters, then all the things you need later on in extracting the oil, Maybe $1000-$1500.
A very very basic CFL grow will run about $200 +/- depending on what you have on hand, and as stated before should produce at least 1/4 ounce each plant, but you are also very limited as to how many you can grow at a time.
Bottom line is that it's a lot cheaper to produce your own, as it goes for anything, vegetables are a great example of that.
As for specific CO laws, I'm unsure on that question.
The strain you buy will also depend on the ailment(s) you plan on treating with the oil.