At the end of the day if you want exotic hardware and unusual operating systems you're gonna pay for it. You want lots o' speed for not a lot of cash, go and build yourself an Intel PC and put Windows/Linux on it.
I'm interested in the Amiga for the same reason I use PPC Macs and old Sun UltraSparcs, they're different and I like seeing how they work. Computers are gonna be reeeally boring when they all use exactly the same hardware and work in exactly the same way.
P.S. PPC architecture isn't dead! Wii uses it! XBox360 uses it! PS3 uses it!