A Dell XPS 13/15 with similar specs will cost the same as its MacBook equal.
There is nothing on the market like the old iMac's... If you buy/build a PC with the same specs, and add a monitor that matches its built-in 5k display you'll probably spend more (the iMacs 5k display is top-notch)
When you match spec's and quality... things equal out. Apple doesn't make a $400 plastic notebook with a crappy display.
But what they do make is a $320 iPad that you can slap in a keyboard case... that will have benchmarks MUCH faster than that $400 notebook.