Well they are $20 a set, so 40% of that would be $8.
Sounded like a fair split to me.
Either you misread it as 80% or maths is not your strong point!?
I've also purchased 2 sets myself, just after all the Rick's I can lay my hands on.
Well 8 plus the shipping. Gotta be at least 4 to ship, rates usually bonkers. And I added a few bucks to make it sound worse!!!
Buy a set cheapskate!