Let's see...I'm getting these things day one. MSRP, and my actual cost with sales in parentheses:
Switch - $300 ($135 after trading in an extra Wii U, which I had made a $50 profit on)
Extra Neon Joycons - $80 ($60)
Binding of Isaac - $40 ($24)
Super Bomberman R - $50 ($30)
LoZ:BotW Master Edition - $130 ($74)
Total with tax on launch is about $350.
For after launch, I already have preordered:
Mario Kart 8 Deluxe - $60 ($36)
PuyoPuyo Tetris - $40 ($24)
ARMS - $60 ($36)
Splatoon 2 - $60 ($36)
Super Mario Odyssey - $60 ($36)
Without 5.5% tax, its out to $491 spent pre-launch. Due to some odd math in how my purchases went, it won't be exact, but it should come out to about $527.