I've got spare copies of some rare fillers available for trade as well:
1x Black Round Corner Shiny/Foil Filler Card
1x M Circle - Black Filler Card (There are only 6 known copies. I've got 2)
1x Two Sides Black Border Filler Card (From Planar Chaos Preconstructed Deck Endless March)
Here are images of some the fillers that I'm missing. The starred fillers are ones that I don't really expect to ever own.





Additional Info:
Black Border with Barcode/Black Border Filler Card- Only 1 has been found and it's NFS

Black Border Foil with Square Barcode Filler Card - 3 Have been found. I know where 1 is and I'm pretty sure it's NFS
Black Foil-White Cross Filler Card- 1 Exists and I know who used to own it, but the current owner wished to remain anonymous
Black Round Corner - Glory Only Date Filler Card - I know where 2 of these are. Both are NFS, but I'm trying to convince one to sell

Black Round Corner Foil Star Filler Card - I don't own one of these yet. I have a source, but haven't made a serious offer yet
Discard Foil with Oval Holofoil Stamp Filler Card - I technically own one, but it's only got a partial holostamp. I'm looking for an intact one.
Fifth Edition Filler Card - I know where it is and need to save up to make a reasonable offer for it

Gold Border Filler Card - I might know where both are, but it might be the same one that was sold. I don't expect it to be for sale ever.
Mandria di Uri/Black Border Stripes Filler Card - 1 person owns both and I'm trying to convince him he should sell me one.