Any computer plummets after a few years, man. I couldn't have sold my iBook Tangerine for full price after three years. At purchase, it was $1599 and had 300mhz IBM 750 (revision A G3), 66mhz bus, 64MB of RAM, ATI Rage Mobilliy 4MB, a 12.1" inch LCD (800x600) , 6GB HD, a 24x CD, and it weighed 6.6 pounds. I updated the RAM to the max for the single slot (576MB), and added an Airport card, which let me run Jaguar acceptably and use wireless until its untimely demise.
In three years, the consumer laptop had leaped me terribly. For $1499, you could buy an iBook in mid-year 2002 that had a 700mhz IBM 750fx, 100mhz bus, 128MB RAM (upgradable to 640MB), ATI Rage Mobility 16MB, 12.1" SVGA LCD (1024x768), 30GB Ulta-ATA 66 HD, and a CD-DVD combo drive, weighing at a sleeker 4.9 pounds, and with another USB port and video out ports.
It was not only cheaper, but all around better. These kinds of things happen in computers, and no system you buy now will be guaranteed to weather the market that long, no matter who your ORM of choice is.