Well, I want to look at this with numbers, and I'm about to make some assumptions. Let's assume that these LEDs are more efficient in getting the light to the plant where it is needed so only 75% of the lumens is needed. Looking on Home Depot's site, an average 13w LED spot or flood light (Philips) is ~$35, and puts out 850 lumens. The same company's CFLs cost around ~$3 a bulb for 23w, with 1655 lumens. Let's say I build a fixture with 8 23w CFLs, that would be a lumen output of 13240 and a bulb cost of $24. To get 75% of that from LED, I'd need ~12 LED lamps with an initial investment of $420!
Rated life of CFL is 12k hours, LED light is 25k hours, so a little more than twice as long. So I would have to replace the CFLs once, let's go twice...and it would cost me a total of $72. That's still no where near the original estimate of the LEDs of $420.
Even if we assume 50% lumens needed, that's still 8 LED lights at an investment of $280. Still being beat by CFLs at $72.
So I'm trying to wrap my head around this, what is the appeal?