My co-worker's family invited a bunch of us to her baby shower and my gift will be money. What amount do you recommend?

My co-worker, who i am friendly with, is the guest of honor at a baby shower given by her family at her father’s house. A bunch of my other friends at work are going. I have decided instead of giving a gift or a gift card, i would give her a check (can be spent anywhere on whatever, whenever). I am trying to decide on a good amount to give. I am thinking either $30 or $50.

what amount do you recommend? or a totally different amount?....