My MH usage is 800x8x365 = 2,336,000 / 1000 = 2336@ 0.0668 = 156.04 / year to run my metal halides. I just paid 60 dollars (total) for 2 replacement bulbs shipped to my door twice per year;
276.04 would be my total per year including bulbs and shipping. I paid $300 for my lights 576.04/ first year.

I would need at LEAST 4 AI SOls to run my tank. Those are 399.95x4= 1599.80 + tax (129.98) = 1729.78 The AI SOL uses http://www.theaquariumsolution.com/led-wattage-ai-sol 75 watts of power per unit. 75w x 4 = 300w 300/8/365 = 876,000 / 1000 = 876@0.0668 = 58.52 / year to run AI SOLs. 1729.8 + 58.52 = 1788.32/ first year.

So for me, it would take 5.5 years (including bulbs) to recoup my investment on the AIs. That's also only using 4 AIs, and I think that's probably well below what the manufacturer's specs are. If my math is wrong, please tell me, I was never good at math!