Computers are a bit of a special case- you can pay over the odds for a Viao, or Voodoo/Alienware etc. but even in the 'normal' scheme of things if you want the latest and most powerful you have to pay for it. You can cheap out like I did and overclock/softmod etc. the hell out of cheapo stuff but if I wanted to play the latest and greatest games at high res I'd have no real choice but to cough up for an A64 and a £200+ graphics card. As it is my main/gaming rig is a Tbred at 2.2GHz with a softmodded 9500 which has lasted me well over a year in its current spec, and I also have a Dual Athlon XP2000 backup/crunching machine which cost me about £150 all in using leftover/secondhand parts. I'd rather have 5.5GHz of FAD crunching power under my desk than one very slightly whizzier single rig.
Everything else in life (cars are the best example) doesn't update at such a breakneck pace, but does depreciate enormously. The answer is to buy secondhand. If I had (say) £6000 to spend on a car I wouldn't have a new Citroen C2 or a Kia Picanto, I'd spend £3000 on a ten year old BMW 740iL, save the rest to cover the higher running costs, and enjoy cruising around in something absolutely superb.