EDO memory
This stuff is so rare nothing on the boardsort list compares
I've brought up EDO ram before.
99% of EDO ram is silver finger,
Yet thanks to an essay that is extensively referenced; that was posted on
http://www.scribd.Com titled the future of EDO (subscription required) we now have a more realistic estimate of EDO in the wild. 140-150 million EDO compatible boards.
Non working EDO sticks are since mid October averaging $10 per stick
Verified working (having some level of guarantee) are past $100 on the high end.
Intel 4000 series CPUs
As long as they have ALL pins completely and complete length sell them DOA (parts/repair) on eBay!
This set of ICs can net you $50-100 easily per chip!
That said even one damaged pin any your under $5 so if it's missing pins you're better with scrapping it. Nothing out there beyond collectors uses a dip 4XXX CPU. And as far as damaged goes it's like coins, anything under mint is only filler because you (the collector) can't afford something ms55+
Cyrix Cy6X86 CPUs
These, in general terms, don't exist and you will NEVER see an authenticated one for under a few hundred dollars.
Absolutely off the assembly line mint they run a few thousand and even damaged (missing a few pins or a few scratches on the gold cap) you can still easily pass the $100 mark.
Less than 2000 were made and around 100 made it out to the public before the line was cancelled and recalled.
A runaway error (infinity loop) in the instruction set can lead to an explosive failure do to heat.
Slocket boards
These boards were intended to let you install a socket socket CPU in a slot processor slot.
Later designs were to go from slot to the later sockets.
The range of these boards is a few dollars to well past $50 for working samples of socket to slot.
Slot to socket boards start in the low 100s!
In general order of value low to high
486/am486 to slot 1
Pentium P525-P5-66 to slot 1
486/am486 to slot a
P5 to slot a
Slot A to socket A
Slot A to socket 7XX
Slot A or Slot 1 to socket 3XX
Slot A to slot 1 (an adaptor for the board)
Slot 1 to slot A (an adaptor for the board)
These boards were in production for less than a year for AMD and less than 2 years for Intel.
Anything outside of the above list is a rare one-off (not literally one but very few)! Many companies fudged around with such socket to slot and slot to socket boards; but the rest of them are so rare you'll get a literal fortune for them; in any state of condition! And you're well beyond the general eBay market with those. Try specialist auction companies. Heritage is my favourite; even if they don't want it they will gladly point you to a reputable company, including competitors!