my favorite LED's:
http://www.stealthled.com/
Another decent company:
http://www.hydrogrowled.com/Default.aspx
That black dog look decent too, though I don't have any direct or indirect experience with them.
Far as finding info there are kinda two levels to it. First you want to do some research on light, spectrum, and photosynthesis. This info applies regardless of the light source you pick, and is really a science unto itself. A first step is to not look into lumens (and related measurements like lux), instead start looking into PAR (photosynthetic active radiation). Lumen is to people what PAR is to plants (at least this is the easiest way to get used to thinking of it).
Once you are secure with concepts like wavelength, kelvin, chlorophyll types and peaks, PAR intensity (moles), etc, you are ready to start looking into leds. This involves researching topics like drivers, emitters (diodes), optics, spectra. You should have an idea of what wavelength emitters you want to mix, what wattage and optics combinations you want, etc.
You can skip all this research and just buy from one of the companies linked here (they all are good). Keep in mind that LED is a 2-4x price premium, and though there are benefits over HID/flo, many people wouldn't see the premium as a value. If you go into LED without the proper budget you will be disappointed.
Edit: Mixing LED with HID isn't bad. HID is often supplemented with cfl's, usually the HID will be up top, and the cfl's will kinda wrap around the sides of the plants to improve penetration. I wouldn't get a hybrid though, if I were to mix led and HID I would want to position the LED's independent of the HID (again I'd wrap the sides and lower portions of the plants with the LED). The cheap panel you linked on ebay is crap. I wouldn't even trust it for supplemental lights. If you want to supplement, the UFO's seem decent for supplemental light.
