Look under fasteners in your local phone directory or search your local web. There are thousands of suppliers out there. Roy Gariepy
Maintenance and Reliability Dept.
Bayer Corporation Dorlastan Fibers Div.
Goose Creek, South Carolina USA
McMaster-Carr has virtually everything under the sun, including thump screws down to as small as M3 and 4-40 in the round head style thumbscrews and as small as 6-32 or M4 in the wing style thumb screws. Enjoy!
Besides McMaster-Carr, there is Carr-Lane and there used to be PIC Design and several other small-component suppliers with catalogs--and don't forget that the Thomas guide is online listing probably every supplier one could think of.