I am currently looking to purchase Greece 10 Drachmai 1976-80 (KM119) and 10 Drachmes 1982-2000 (KM132). This is the coin with the imaginary portrait of Democritus (the philosopher credited with the atomic theory of matter) on one side, and an atom symbol on the other.
I will pay US 50¢ per piece for any quantity up to, say, 100 pieces, plus reasonable postage to me in Fort Worth, Texas. I'm hoping that, for those of you who are in the habit of searching through dealers' "junk boxes", that is enough incentive for you to make a note to pick these out when you see them.
Now, you may wonder what I want these things for, and in such quantity. It's easiest just to show you.

In case you're curious, that's matte-board, scraps from my own projects and from local picture-framing shops, cut with a laser to get the dimensions
just right, so that the coin stays firmly in the hole and does not fall out. I first made "coin cards" like these with the Luna Project medalets struck from the die shown in my profile picture, and in the not-too-distant future I hope to have new pieces of my own design to do this with.
I will also offer US 50¢ each, plus reasonable postage, for the Mexican "Sor Juana" $1000 coin of 1988-92 (KM 536). These are so thick, and in such low relief, that I want to experiment with overstriking them, so I anticipate needing a couple of dozen for that purpose.
For those who have viewed this post in the past, yes, if you happen to have bulk quantities of Britain or Ireland large-size 5p or cupronickel shillings ; Australia, New Zealand, or Jamaica 10c ; Singapore or Malaysia 20 cents/sen ; and other 5·65 gram 23·6 mm coins of 75 Cu 25 Ni composition which I can use to slug my German payphones (they're close enough to the 5·5 g / 23·5 mm of the 1 DM), I am still interested. But at this time I do have a couple of thousand, and I haven't yet started overstriking them with my own dies, although that is still definitely on the agenda. So my need isn't urgent.
Here's an explanation of what I am using those coins for.