One point I'm trying to make with this series on old computers that we don't have to buy into the assumptions of planned obsolescence that companies often try to foist on consumers in order to make more money. In fact, with nearly 7 billion people on the planet today, our collective environmental impact, including from peak oil and global climate change, will force us to make more conservative use of our natural resources in the 21st century than the United States and other industrial countries ever had to consider in the last half of the 20th.
If we continue to treat computers and other electronics as merely cheap and disposable products, and don't give any concern to reusing our older equipment, then eventually the new products will become more expensive due to higher demand and lower supply of raw materials, and they'll probably be of lower quality, because when people don't expect for something to last for a long time, they're less likely to demand (and be willing to pay the slightly higher price for) products that are designed to last.
Where hardware is concerned, you do often get what you pay for, and high-quality components that were expensive when new are often available used for a tiny fraction of the original price. The Apple IIe (Platinum series) and Apple IIc+ (upgraded to 8MHz) that I recently purchased on eBay for $154.70 and $249.99 respectively were admittedly nostalgia-driven purchases, but they are so solidly built and the keyboards are so nice to type on that I was willing to pay the price. They were also extremely expensive computers when new: I would never have paid $750 in 1988 for an Apple IIc+, or $1400 for an Apple IIe, at a time when an Amiga 500 cost about $550, and was far more powerful, but now that I own one of each, I can almost see why some people were willing to pay such high prices for Apple II gear.
One area I will spend a lot of time covering is the SCSI bus, as this is the interface used to connect hard drives, CD-ROMs, and tape drives to many of the older machines, including my Amiga, Alphas, and VAXstations, and there are a number of tricky details to cover. Some years ago, Seagate released an informative white paper explaining why SCSI drives almost always cost more than the IDE drives of the same era. The differences were all related to the higher performance and reliability requirements of hard drives for the server applications where SCSI hard drives were used, and the lower prices that users were willing to pay (and willing to accept lower performance and reliability in exchange) for IDE drives.
In the paper they mention a typical MTBF of 1,000,000 hours for a typical high-end SCSI drive. That's over 114 years of continuous usage! Now I have no idea how manufacturers justify this estimate without a time machine, but the point is that these are the goals that the drives were built to achieve. I had to go through 5 or 6 different 36 GB SCSI drives before I found one that was quiet enough to put in the Amiga: most of them had annoying high-pitched whines, and I have extremely sensitive ears. Fortunately, I live near Weird Stuff, which has an excellent selection of used computer gear and a good return policy. for this project. According to smartctl, it had a lifetime usage of 13756 hours (about 1.5 years) when I bought it (the drive itself is probably about 10 years old). If I'm lucky, this drive will last another 20-30 years, and hopefully the Amiga itself will also last as long.