Some of you may remember my old thread about my Gamecube collection being worth $1300 (it's now worth $1400!). https://gamrconnect.vgchartz.com/thread/242666/my-gamecube-collection-is-now-worth-1325/
Well, GameCube games used to be stupidly cheap, back in 2011 or so. But as the Cube got older those games went from being "last gen" to being "Retro". You can see here that GameCube game prices were at an all time low in 2011. https://www.pricecharting.com/console/gamecube But that same chart shows prices steadily climbing until we've reached the 2020 insane prices. I believe that the same thing is about to happen to Wii games. Right now Wii games are at or near the bottom of their price curve, as you can see here. https://www.pricecharting.com/console/wii Most consumers view Wii U and Switch as the same generation for Nintendo, which causes them to also view Wii as "Last Gen". But I believe that in the next 5 years Wii games will start to be seen as retro, and prices for them will Skyrocket, just like they did with the GameCube.
TL/DR: GameCube games were once stupidly cheap, and are now mostly unaffordable. Wii Games are stupidly cheap right now, but are about to become mostly unaffordable in the next 5 years.