I've had a couple best finds.....
IBM PC-330 100DX4
An old roomie got this at the bank where she worked. It came with an IBM G40 monitor with a damaged cord, an IBM Model "M" keyboard in pristine shape, and a Compaq PS/2 mouse. It's not a very collectable system I know, but I owned it for about 5-7 years, used it really hard (running Windows 98 SE on 64 MB of RAM). How much did I pay, just time to fix her other computer which was faster.
The Three Laptops on E-bay
I had wanted a cheap laptop to fool with, but all efforts on E-bay to procure an older 486 laptop proved futile. I either ended up with a DOA Twinhead, a working Twinhead missing parts (including the uber-rare and expensive power supply), and a quazi-generic (ProStar) with broken LCD hinges. So I searched around on E-bay under the term "Oddball Laptops" and came across an auction for a Duracom 5110D (same as my Prostar except with a colored screen), an old Ergo 33 MHz 486 (which I jury rigged and used till the LCD died), and an AT&T Safari complete with 540 MB Hard Disk and (then) working NiMH batteries. I still need new batteries for my Duracom 5110D though, and more RAM. I could probably make it a decent Windows 98 SE box someday.