Did you check D Lawless? I bought some nice small screws from them for my hexagonal bin about 9 years ago. I think that they were #5 pyramid screws but they have some
round #2x1/2. Not slotted but they do have #2. Note that a #5 is only 1/32" bigger so you might be able to simply enlarge the holes if you want the pyramids. The screws are cheap but as I recall, the shipping is not free so you might want to stock up on various sizes of small screws while you are at it.
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.