Short form: If you're at a senior level already (10+ years exp) it's not worth getting the PMP if you only have 5 years left to work; people will look at your experience (your concern) much more, and the PMP's just a dressing.
Longer form:
Where do you live? In Australia the PMP / Prince2 are almost foot in the door certs ticked off by HR; the hiring manager's much more interested in whether you have delivered something similar before. I have heard that the U.S. places more value on the cert, but again your concern is valid. Project managers are a dime a dozen, so hiring managers look increasingly at their exact experience. I'm on the PMO-side of work, so I thankfully don't get scrutinised as much there.
This being said, if you are interested in the profession, the PMP is a good investment; I often find myself referring back to the PMBOK when out in the field. You can do it for $600-ish all up if you join PMI (which itself is tremendous value) then just register for the exam. Most course hours can be gained for free through Udemy/Coursera.
Back to the PMP, it sounds like you may not have the necessary 4,000 hours project management experience to qualify for the exam: you'll need to write proof of going through a full project from initiate to close. Also look around Udemy or similar for free online courses; these count towards the required 20 hours training proof. Finally, for test practice Oliver Lehmann is the gold standard; his practice test is harder than the real thing and serves as a good gauge of your knowledge.