Yeah if you buy that AEG then buy all the other stuff they've put in/on it, factor in the time to make it and then make a profit it's going to cost something like that... ish. Big whoop ?♂️
I've got a standard AR AEG build going on at LC's Engineering at the moment, will cost me a couple hundred more when all is said and done (spread out over many years), but it'll be far better in many, many ways. At least as far as I'm concerned personally. Most airsofters don't actually posses the depth of nerd knowledge relating to AR/AR AEG parts to know how to put together such a build though; sorry if that reads as pompous but believe me I do badly enough with the ladies to ensure you it is not - just a raw fact.
If you want a super duper gucci gun and you have the money then obviously there's lots of platforms you can choose from but I'd say the AR AEG probably has the widest choice of parts to use and hence most customisation potential, especially if you have/know someone that has a good die set and a mill. Which is ironic because my own build when finished will look super generic and boring to 99% of people despite the rarity of the parts used, but I'm an objective weirdo like that.