HI Steve,
I just bought a load from various eBay listenings (I must have ordered 20 different types). One thing to watch out for though. I used the 4-40 stainless steels crews and these were fine. I then tried longer high tensile steel screws of the same size, but these ended up sheering their threads and slightly damaging the threads in the bridge. So now I'm using 6mm M3 grub screws, these are a tighter fit and basically re-threaded the bridge but it seems sturdy and strong.
Regards,
Paul