Worth it: usually yes, IF you can wait for compounding. Local SEO (profile, reviews, citations, service pages) shows movement in one to two months and keeps paying rent-free for years, which paid ads never do. Not worth it: when this quarter's revenue is the emergency; that's a job for demand capture.
DIY is genuinely viable for the local layer: our checklists cover the one-time setup, and the ongoing work (reviews weekly, one real page a month, quarterly profile checks) is discipline, not wizardry. Where agencies earn their fee: competitive markets, technical cleanups, and content at scale.
The self-test before paying anyone: do the free foundation first. If you won't sustain the free habits, a retainer mostly buys you reports about habits nobody's doing.