The trouble is that the Kelvin rating of the bulb is entirely manufacturer-rated. There is no regulation or anything resembling it. It's probably just the brand you bought. FWIW, I wouldn't buy eBay brand halide bulbs, I'd stick with something known to be good because the PAR value of halide bulbs varies HUGELY. You could be wasting electricity on bulbs that are delivering very little usable light.
Reef Supplies has a few halide bulbs at good prices.
http://www.reefsupplies.ca/online-st...-halide-bulbs/
If you don't see what you want, Ray is great to deal with, send him an email and see if he can get what you're looking for.