It's decent... I had 3 frags to go.

550 to get 50% + 20 for the capsule = 570 / frag

Pulled thrice, RNG was good, I got my last 3 frags for 1710 coupons.
I've heard of another theory of diminishing returns, if you're pulling for more. Theory is to go somewhere in the middle 30-40% where it becomes more cost effective.
End of the day, it's still RNG. You could have 50% and still keep hitting 0s.