How to thank the fertility clinic?

Dee • 42, happy mother of a lovely boy through ICSI on 3rd round. TTC #2 since June 17
Hello everyone! 
I survived infertility and got pregnant after 3 years of trying. 
Now that my baby is born I would love to thank the staff of the fertility clinic for their work and constant encouragement. 
Do you have ideas what - apart from a baby-thank-you-card - I could do/buy to show my gratitude?