Anto,
When I've found myself in need of new mudguard stays, I buy PlanetBike spares, available here:
http://ecom1.planetbike.com/smallparts.htmlThey fit the SKS mudguards just fine. I also like PlanetBike's fixing hardware -- instead of 8mm, they used 10mm nylock nuts. I find they tend to stay more secure in the sort of riding I do. The polishes stainless stays and hardware PB uses seems to stay shiny longer than other brands'.
Best,
Dan.