Collecting Salesforce Certifications is one of my favorite pastimes for a variety of reasons. On the most logical level, getting certified is the best way to display on your resume that you actually know what you are doing. On a more personal level, getting certified feels like a big win and it's a huge confidence booster.
I have completed seven Salesforce certifications in 2019, which is not normal and not sustainable. In other words, I doubt I will have 14 certification a year from now (but you never know!). For now it has been a wild ride, and a fantastic career switch.
I have also failed two tests. One was a test that I had no business taking (Commerce Cloud Developer) and the other I passed with a second attempt (Marketing Cloud Consultant). At face value I could have conceivably spend $1500 this year taking Salesforce Certification tests ($200 per first attempt, $100 per retake).
However, there are ways to minimize these costs. For example, whenever Salesforce hosts Certification Days sessions, they usually follow up with some sort of discount on the certification tests.
Additionally, they periodically have free Beta tests. This is when they are developing a new test, or revamping a test, and they want experienced users to take the test for free. The upside is that it's free. The downside is that it's longer and you don't really know what to study for. For example, I took the Marketing Cloud Administrator Beta test. It was 180 questions in 180 minutes and I used every single one of those minutes. My method of studying was one trailhead created by Salesforce, and all of the implementation guides. Reading implementation guides is pretty low on my list of fun things to do in my free time.
That being said, Salesforce is currently looking for Beta testers for a revamped Salesforce Certified Pardot Consultant. The only prerequisite is the Salesforce Certified Pardot Specialist Certification. This survey will be closing any day now, but I encourage you to follow Salesforce Success groups and follow @marketingcloud and @Pardot on twitter for opportunities.