-snip-
Some things, the PS4 is nearly 4 years old, so cost goes down, it is good for its cost because you can't take your ps4 on the go (oh but you can use the psvita as a low-res screen and controller!!) and tell me how you're going to fit a hard drive in the Switch, I really want to know.
Also just wanna say age is relevant in price as throughout time things get cheaper.