> You can get a 1.67Ghz G4 Mac Mini on eBay with OS 9 preinstalled. It's wicked fast (especially with an IDE SSD adapter)

The fastest Mac mini G4 topped out at 1.5 GHz, not 1.67. I'm the guy selling many of those Mac mini G4s upgraded with SSDs on eBay... just a hobby business. Also sell on my website at https://os9.shop where there's a FAQ where you can read more about it and why it's a good model/upgrade to buy or build yourself.