well i read about the pricing so it is a bit different as thought
max 31,5 kg --> 84 € shipping to usa
25kg --> 64€
so i would propose for about 20 keyboards = 60 € + 64Shipping to USA + (shipping from seller to me, about 7-10 €)
sow about 130€ / 20 Keyboards = 6,50€ each keyboard including shipping (6,50€ = 9,50$)
so this keyboard would cost you about 9,50$ international shipping included
+ domestic shipping i think about 5$ for a box in usa or?