I found two old Dallas and two old Intel parts in my office.
Available for free.
(Shipping might be an issue, depending on where you are. I'm in Maryland, USA.)
To the best of my knowledge they are brand new, never used, never installed, power never applied.
(They might still work ?!)
Qty. 1 of each.
Dallas; DS1287; "Real Time"; d/c: 9914B4
Dallas; DS1220AD-100; "Nonvolatile SRAM"; d/c: 9517D1
(I can even give you a solder tail socket for each of the Dallas parts, if you ask.)
Intel; D80287-10; math co-processor (?); DIP-40 600 mil; d/c: L9500030
Intel; D80287-8; math co-processor (?); DIP-40 600 mil; d/c: L8311507
You can respond to this posting or off-list: MRILEY@AVT-HQ.COM
Best regards, Mike.