two main factors that I can think of. The walkera parts are straight out of china (well so are every other part =P), and they probably do not have a middle man, as well as CS, or QC or as tight of tolerances, who knows. Any one of those factors really raises the price.

The walkera from what i hear is not a bad heli but the electronics are horrible. If you can get it arf some way and then put your own electronics in it then you'll probably have a decent setup =)