Assuming that a Designer should get certifications :)
Red Dot Design Award, designer of the month, Dribbble 100k club, blue tick on twitter, designer who knows how to code, best girl-/boyfriend
Even though I came here to write the exact same comment this still made coffee come out through my nose lol
I think just having the trust of your current and previous clients should work. Also, your work can speak itself.
It's always good to have a few certifications to show. Now these wont guarantee a job or an internship but it can become more of a conversation point with your peers or whilst in an interview. I would suggest less expensive ones like Interaction Design Foundation (IDF) (http://interaction-design.org/) or take up a basic HTML CSS course from Coursera.
TIP: While taking these certification make sure they allow Linkedin integration!
In terms of UX: A license to practice design.
Having a certification from NNg just because you had a two weeks workshop means jack shit. As long as what you design affects the life of real people design should be licensed just like medicine.
Design being licensed like medicine is an awful idea. Art affects people, too, maybe artists should be licensed?