Where to buy screws that hold the joysticks?

Like the tittle says...

I did a joystick upgrade, but to my horror one of the screws got stripped. I've asked Steam support about this & they said that the best bet is to ask on this website.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 1
crwdns2934285:0crwdne2934285:0