The 3DS was $250 USD at launch in 2011. The Switch is $300 for launch in 2017. Six years of inflation put them at roughly the same price. Maybe it is different in other countries?

You can't compare a console launch price to the current prices for older consoles. Every single console has launched at a high price to take advantage of early adopters who will pay that much. It will go down once those people have all bought it. This is straightforward economics and every console or handheld has done it this way.