A German outfit (schraubendepot on Fleabay) has tiny brass (messing) flathead (senkkopf) woodscrews (holzschrauben) in pkgs of 25 or 100. They have a large variety of sizes, cost is very low (about $3 US for 100), very fast delivery, and they have an English speaking lady on their staff who can help you.

I just bought some 1.6mm x 8mm screws from them . . . go to item 370116181631, then look into their store. The little screws are on about the 3rd page.