Now we've got a good handle on the most important choices, disks and bus and processor and video. The rest is easier, and less dependent on the peculiarities of Linux.
Next in importance is your CD-ROM drive (you'll almost certainly be installing your Linux from it!). You have a SCSI system, so get a SCSI CD-ROM. That's pretty much the end of spec, as SCSI CD-ROMs are a very generic item. The only significant price driver is their speed -- 6x, 8x, 10x, or up (it's hard to find 2x or 4x speeds anymore).
Again, bear in mind that you probably don't need the latest and greatest. High-speed CD-ROMS are really designed for people playing CD-ROM games or other applications involving image and sound archives. If you're doing the Linux thing, chances are you'll primarily use CD-ROMs that are code archives. Your average transfer size will be small and an apparent speed of 6x or even 4x quite satisfactory. So here's a place to cut costs by buying well behind the leading edge.
Next, consider a backup device. This is another place where spending extra money pays. Cheap tape drives are unreliable, noisy and have agonizingly slow transfer speeds. It's no fun to listen to what sounds like a blender dicing celery for twenty minutes while your disk is backed up, so with the cheap drives you'll quickly find you're backing up less often than you really should.
The worst are the QIC mini-cartridge drives, including the new Travan technology. But they're also the cheapest, and thus exactly what clonemakers tend to bundle and salespeople to push. Avoid these. Quarter-inch QIC drives are less nasty (mainly because they have higher transfer speed and get done quicker; also they're usually engineered better for reliability). But you really want to pay for a DAT or DLT drive.
Of course buy 16MB of memory, unless you really like a text-only console -- X is not comfortable when memory is tight. Having lots of free memory will also improve your virtual-memory performance. Fortunately, with RAM as cheap as it is now this is unlikely to bust your budget.
You'll also want a three-button serial mouse. I happen to like the three-button Logitech MouseMan and its kin, just the thing for a hacker's chronically cluttered desktop. Your mileage may vary.
You'll want a modem, of course. 28.8 for speediest possible net surfing. How to buy a modem could be in an article in itself; we won't try to cover it here.
The rest is basically frills and freebies. You can get a sound card if you like, though under Linux you're not likely to use it for anything but playing Doom. Every system sold today has the requisite two floppy drives and two serial ports and one parallel port.
And that about does it for basic hardware. Later on we'll look at some actual system configurations.