I wish they'd talked about running costs as well as the price of parts in the 'costs' section. It's the electricity bill that puts me off. Unless it can be... solar powered?
"Full-spectrum LEDs seem to output about 75 lumens per watt, so if our panel is 20k lumens then we should expect our panel to draw 266 watts. This seems reasonable to me. If you leave it on 8 hours a day, you’re going to use 25 cents per day in electricity (at $.12 per kWh)."
Almost anything can be solar powered.