The Wii was beefed up enough from the original GameCube to (just about) qualify as a 7th-gen console, albeit a low-end SD one.
Wii also combines a relatively strong GPU with a relatively weak CPU (way, way behind the Xbox 360, PS3 or modern PCs).
This reminds me of the design philosophy of the SNES (the exact reverse of early 90s PCs) - some advanced graphical magic coupled with a sh*tty CPU.
As for old Amiga hardware on eBay, I noticed 68060 accelerators still go for stupid money, to say nothing of PowerPC boards.
Looks like my A1200 will stay ultra-retro 14MHz for the forseeable future. (While WinUAE kicks a virtual 300MHz or higher!)