FWIW, just having a certification means very little. I have certifications that I'd like to think make me better at my job. Then I look towards some of the more troubling professionals in our industry that it feels I'm cleaning up after, who have every certification under the sun but not the appropriate appreciation for their craft.
When the company I work at is hiring, we think very carefully about which certifications someone has and why they have them. Do they have them because they had a yearning to learn more about their craft, do they have them because they "bought" their way into this
line of work, or do they have them because they were required to get them? Why you get the certification is in some ways as important as the certification itself.
We also look at work experience. No matter how driven a person is to work in a particular field, there are many subtleties of working in a given field that you only
pick up by having looked at similar problems many times in a wide range of different circumstances. This goes for the technical nuts-and-bolts aspect of a craft as much as it goes for understanding the communicational dynamics between your position and the positions of people around you, as well the between those people and the people they have to connect with.
Also important to us is a willingness to learn. Someone who thinks they have all the answers and lacks a capacity to learn more on their own without being forced to is a candidate who is destined for disappointment.
My advice is work your way up into the industry. You can try "buying in" but I don't think it'll get you where you want to go. Eventually those certifications will either make complete sense for you to invest in or your employer will see you have the skills and value necessary to invest in you by covering your certification expenses.
Also seriously consider the questions likely to show up in a job interview. If all you have to show for a rigging background is that you've got a certification, don't think it won't be apparent to your interviewers that you don't fully know what you're talking about. It's not that you *should* know all these things already at this
stage of your career -- it's that you *can't.* You just haven't enough field experience to have looked at the same problems many times under many different circumstances with different levels of resources available to you for problem-solving.
If you're driven and passionate about rigging, not just as a job but as a craft, you'll get there. If it's a thing you're casually interested in for what may turn out to be a small fragment of your life and long-term career path, keep soul-searching because potential employers have many ways of filtering out the people with casual interest from the people who have a seemingly superhuman appreciation for their chosen craft.
Most importantly. Ask questions, lots of them. There's this tendency in people who are treading into unfamiliar territory that there's an expectation of them that they already know everything. That's BS. An incredibly substantial aspect of any professional's spectrum of responsibility is knowing that it's okay to not know everything -- to realize that there will always be projects that will challenge their creative minds to go seek new information. Always be humble enough to recognize when you need new, more, or clarified information, and then go out and get it.