If like me, you only want to play games, the following would be enough:
Desktop A1200 with Blizzard 030 and extra RAM
External SCSI CD ROM Drive
Squirrel
Internal 2.5HDD
I don't even need that much. I've got an 030 with plenty of RAM, a 4GB 2.5HDD, and a PCMCIA Compact Flash reader for transferring files from PC. I have an IDE splitter that will let me use an external IDE CDROM, but I dont think I actually NEED that for anything. The CF card does the job.
From what I've seen, Squirrels are pretty expensive. Unless you really need SCSI, just grab an IDE splitter. And if you're just playing games and demos like me, you probably don't even need that much.
Stuff like a PPC/060 and Mediator are gonna cost you a big chunk of cash. Unless you're doing pretty fancy stuff on your Amiga and really need that stuff (or unless you luck out and get a great bargain on the hardware) I wouldnt get them just to have them.
If you do want all that I think Everblue's list is pretty good, though you could also do a flicker fixer/scan doubler rather than Voodoo card to get VGA output that could also be used for games.