Because it's as good as anything that Sideshow has done. Blackcat is essentially Marvel's Catwoman and the Sideshow Blackcat PF isn't any better than this Catwoman PF from DCD.
Sorry, but I highly doubt it.
DCD's products may look acceptable in promo pics, but I assure you that once released they usually leave much to be desired.
SS quality control may not be the best (euphemism) but at least you can see some quality in many of their products. A question of taste I guess.
I don't know, I would certainly wait for that AH! Catwoman that was teased at SDCC.