Honestly, I find the US price for the dock set quite reasonable. It isn't perfect, but it's just below the amount before I'd begrudgingly pay for it. At $80 you're getting the dock, 39W AC Adapter and HDMI cable, and the whole set is massively cheaper than the competition, where a standalone Surface Dock costs $199:
https://www.microsoftstore.com/store/msusa/en_US/pdp/Microsoft-Surface-Dock/productID.325725200
I mean, accessories are always going to have some degree of profit margin attached to them, and while the cost of production for all the individual components isn't high, you've also got to factor in the shipping costs and weight of the set, and the fact that it's far cheaper than competing docking solutions and also far more generous - you get everything you need here, and it's all included with the Switch anyway.
I'd also expect there to be an opportunity cost associated with selling these, make them too cheap and you end up manufacturing more docks/AC Adapters/Nintendo-branded HDMI Cables, all of which could have gone with the Switches themselves.
Still, it's good that people continue to question the prices of peripherals rather than accept them, if you compare the Switch, a hybrid device, to Microsoft's Surface, a hybrid device, it's a day-and-night difference:
Switch: Tablet, controller input and TV/Monitor dock included
Surface: Tablet included, controller (Type cover) sold separately for $110, TV/Monitor dock sold separately for $199.
Only one of the two devices actually performs all its potential hybrid functionality out of the box.
£3.99 for a USB C cable is a premium? Their proprietary 3DS chargers cost less than £10, you cannot tell me that £25-30 for an industry standard connection is fair pricing.
It's not a USB-C cable, it's a 39W power adapter, and its priced cheaper than competing USB-C power adapters that deliver similar ranges of power (Apple's 29W USB-C power adapter is twice the price, at £50, Dell's 45W adapter is $60 (so £50)).