We are just going to assume, for the sake of conversation, that we all live in a state where there is a medical cannabis community and laws that protect the sale of cannabis. Let us also assume that all the proper documentation and licensing is present and this operation is approved by the landlord.
Okay, so with that out of the way...
Be aware that it will take considerable time and a more considerable investment. You will need time to procure the property. Purchase the equipment and supplies. Prepare the growing space. Grow the product. Properly dry and cure the product. Then build a reputable customer base.
As a provider you also need to develop your own reputation as having a reliable stock. No sense in having only so much, when you run out then all the customers you had will now be inclined to look elsewhere. So you'll need to gauge your business appropriately with the supply and demand aspect.
You will need to decide on a system and a method, perpetual or single large harvests, hydro or soil? You will be limited when renting with regards to the amount of lighting you can use. A 15amp circuit can't run much more than 1800w (and even there you are pushing it), and when you consider in ventilation and other electrical requirements a single 1000w system or two 600w lighting systems are your best option.
To run a perpetual grow you will need access to clones, either made by yourself in a vegetative/mother room, or acquired from other reliable growers. I think given the situation you provided that running seed to harvest might be your best bet rather than a perpetual grow.
What method you choose will depend on two factors. How much time and attention you can dedicate to the grow and how much money you want to invest. Having two ounces per month is 1.5lbs per year (24 ounces), which is completely possible. I think you could produce an adequate amount with a 600w system and only 3 harvests per year even as a new grower so long as you don't skimp on your environmental controls and you do your homework.
Figure a single 600w system, a hydroponic system (pick your poison), nutrient system, pH control, Air Conditioning/dehumidifying, and all the other odds and ends is all going to add up to around $1000. You could spend more, you could spend less, but there abouts is a pretty good budget. With any luck you'll be able to easily grow as much as 12 ounces without much trouble in just a single grow. This will help pay for the cost of the system and give you a little wiggle room for improvements and changes down the road. It will also give you a nice "buffer" for the next few months in the event that there is a crop failure.
Over producing is like insurance. Grow more than you need and jar it up if you cannot move it. If powdery mildew, or bud rot, spider mites, electrical or mechanical failure, or any other of a number of disasters that could destroy an entire crop do happen you'll be glad to have a buffer.
Then, if your volume is high enough you can reduce your prices, say a more friendly price (I'd never pay more than) of $280 to $300 per ounce and move that weight to your loyal customers. When your stock is lower you explain that was a "one time thing" and the price is more like $400/oz. There's a lot of ways of going about all this. building your customer base, and keeping them happy, will be the hardest part of any business venture.
