Mikes generalized Apple II keep list, kindly correct me for dumb stuff.
Systems
They have to be pretty nice looking, systems with school ID engraved an
inch high on the front are not desirable.
Apple II, the orginal machine
Apple II+, still not too common
Not the IIe, sorry parts only, too many of them.
IIgs, not rare, but people still actively use them more than any other II.
Look for Woz editions and rom 3.
IIc, cute and complete systems with monitor still sell for $35 or so.
IIc+, more powerfull than the IIc, but in some ways less collectible (no
idea why), still $45 for a complete system is fairly common.
Drives (mostly I mean external)
Any external hard drive, or even case.
DuoDisk floppy drives (two drives in a box) with cable.
Unidisk floppy drives
White IIc drives
400k floppy drives
1.44 MB floppy drives
Keyboards
A9M0330 is the IIgs original keyboard, and VERY popular because it is the
smallest mac keyboard (and its the original.
Any mac keyboard, I even pile broken ones in a box for parts. This comes
from actually paying $169 for one once.
Mice
Early DB9 mice, M0100 with the black ball retaining ring is the original.
All the mice too.
Misc
IIc LCD display
IIc 9" green monitor AND matching stand.
Kensington system saver fans.
Cards and other innerds
Accelerator boards, Applied Engineering Transwarp about the most desired.
Fast SCSI cards, much faster, only card that supports removable media.
Apple Rev C SCSI cards, but much less so than Fast SCSI.
Workstation cards
Vulcan hard drive inside power supply
Focus IDE drive on a card
Anything curious
I/O controller cards (for later floppy drives)
Mouse cards for IIe