I work part time at a Fastenal and noticed that there are some brass screws that are quite cheap. I am assuming that since they are 'slotted' screws that they just aren't selling. Some are tiny but not all.
https://www.fastenal.com/products/details/0152108?r=~%7Cisclearanceitem:Yes%7C~%20~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600051%20Screws%22%7C~%20~%7Ccategoryl3:%22600071%20Wood%20Screws%22%7C~%20~%7Csattr02:%5EBrass$%7C~%20~%7Csattr04:%5ESlotted$%7C~
https://www.fastenal.com/products/details/75375?r=~%7Cisclearanceitem:Yes%7C~%20~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600051%20Screws%22%7C~%20~%7Ccategoryl3:%22600071%20Wood%20Screws%22%7C~%20~%7Csattr02:%5EBrass$%7C~%20~%7Csattr04:%5ESlotted$%7C~
https://www.fastenal.com/products/details/0152108?r=~%7Cisclearanceitem:Yes%7C~%20~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600051%20Screws%22%7C~%20~%7Ccategoryl3:%22600071%20Wood%20Screws%22%7C~%20~%7Csattr02:%5EBrass$%7C~%20~%7Csattr04:%5ESlotted$%7C~
https://www.fastenal.com/products/details/75375?r=~%7Cisclearanceitem:Yes%7C~%20~%7Ccategoryl1:%22600000%20Fasteners%22%7C~%20~%7Ccategoryl2:%22600051%20Screws%22%7C~%20~%7Ccategoryl3:%22600071%20Wood%20Screws%22%7C~%20~%7Csattr02:%5EBrass$%7C~%20~%7Csattr04:%5ESlotted$%7C~