Mirko, your shelf scares me. Your most expensive snares are on the top, so if they fall, they will hit the hardest. On my flat shelves I put a strip of skid resistant tape across the front so if I am playing and there is any wall vibration, the snares will not creep off the shelf and fall. To store upright, the safest option is to look at how tire dealers normally stack their tires. Simply two straight rods, the tires (snares) sit on the two rods and cannot roll out.
You could rig something as simple as two broom handles running parallel. For extra protection, you could put those foam floating swimming noodle tube things from the dollar store.
In restaurants there is often a coat rack and on top they sometimes have a flat rack made from 3 or 4 stainless steel rods. If you can find one of those, simply remove the centre rod(s) and you will have a nice factory built rack.