white LEDs have been the last to come on the market mainstream. red, yellow, green, etc. (mostly for traffic signals and stop/turn) have been around longer.
expect white/blue to be more expensive. still not commonly available in 120 volt configuration (for home lighting use) or in sealed beam focused spot configuration in any voltage. about the only place you'll commonly see white is in low voltage flashlights and worklights.
and yes, you pay for the diodes and circuit boards with any LED, so they are more expensive. generally not worth it unless you have a situation that demands low wattage or low heat production (solar home/RV/camping/industrial, etc....)
however, unlike compact flourescents, they actually do live up to their lifespan claims and may be worth it in the long run if you can live long enough to see the payback time....
amp