>>37757327$300~ for the Switch, if there's a new one incoming there will be a price drop but not so much
$60 for the game
$20 for online
$5 for Pokemon Bank
There's probably going to be a Pokeball Plus Pro that contains a mythical Pokemon, that'd be $50.
Then comes the accessories; you need a screen protector, a case for your Switch/dock/etc, at least $20+ for a 128GB microSD card from a reputable and reliable brand (Sandisk, Samsung, Lexar) and the Switch Pro Controller that is $60. Your mileage may vary but you can easily drop close to or beyond $100 for accessories alone in addition to the 4 required payments above.
Meanwhile the barrier to playing 3DS games is pretty easy, the 2DS tablet is $90~, the 2DSXL is $150 and the New 3DSXL is at $200+. No shit Nintendo is trying to make a cheaper Switch.
Then the Gen 4 remakes and the second set of games will come in 2020 and 2021 respectively, that'd be an easy $120. Around this time Nintendo will also release an upgraded Switch to compete against the new Xbox and PS5.