I mean those are all the most expensive possible sources for those parts, and it's the usual thing of slapping random accessories on to inflate the price.
He's asking Viper Tech money for it, y'know. It only has two magazines.
Sure, importing is cheaper but it's in my opinion a moot point when it comes to pricing second hand airsoft replicas. Plus once ProAct slaps on their 60 odd quid shipping or whatever it is these days and then 20 odd percent of the value for customs fees THEN handling fees as well suddenly that 396 becomes 560