Apple had to pick Be, Inc. or NeXT (who had Jobs). They went with the latter. Be, later on, went to Palm, but that was too little, too late.
SGI was one of the many Unix mastodons who fell victim of PC hardware (x86-32, then x86-64) and Windows NT, Linux being good enough, with Apple taking the piece for graphics designers and audio engineering (many whom came from Amiga, and SGI). Oh, and I forgot to mention: they bet on the Intel Itanic.
I wouldn't pay a dime for these nowadays. Way too slow / inefficient W/performance. Which is really sad, but with current energy prices I just wouldn't be able to afford my Octane 2 using 1 kW anymore. I owned many SGI machines, really loved them (the sound card in the Indy was insanely good! And IndyCam from a time when hardly anyone had a webcam). Indy (various, including Challenger S), Indigo (including purple remake), Indigo 2, and Octane 2. But never an O2 :) nor a Fuel or Tezro ;) cases, although plastic and sensitive to scratches, were great aesthetical, too. While I would not want such machine anymore, I will cherish the memories though! Plus, there are some people reusing the cases. Cool beans! IMNSHO, SGI machines like Indy belong in any half decent Unix museum.