Since you are sure that you are never going to grow more than 1-2 plants, I recommend making your space smaller. A 250W will cover a space about 2 x 2. I did a small grow ( 2 plants that were scrogged) in about 4 sq ft with a dual 150W HPS that did quite well. You can certainly grow a small personal supply. You may want to look at some different training methods that will help maximize your yield. Since your space is small, you may do better growing SOG as your veg time is cut down. I don't have much extras money every month either. Keep your eyes open for good buys on growing supplies or things you can make into growing supplies.
You need good ventilation, regardless of the heat. A continual supply of fresh air is necessary for photosynthesis. Good light and good ventilation are a must for good qualtitry and quantity. You do get out of this what you put into it.
