I'm ready to upgrade my current system: A 4 ft. twin bulb high output T5 system with a mix of 6500k and 3000k bulbs. I am able to grow about 4 healthy plants with this system up until they are about 1 foot tall, but beyond that, the results are not wowing. I do get fruit, but probably 40% of what I would with a 6 or 8 bulb system.

My goal is to grow 5 to 6 plants to maturity (indoors) without supplemental sunlight. What is the most cost effective way to achieve this goal? If at all possible, I'd like to stick with high output fluoros. I know about the "very high output" systems, LED, and Metal Halide / High Pressure Sodium units, but I'm really trying to steer away from that for electricity reasons, total equipment cost, efficiency, upkeep, and heat distribution.

Any constructive, practical advice would be greatly appreciated.

Growing mostly chiles, tomatoes, strawberries, herbs, flowers, and I would like to try a dwarf citrus tree as well.