Here is the honest version, no thumb on the scale. The cheapest sticker is a DIY hosted builder — call it $9–$40 a month on annual billing, more once you add apps and a business email, which is roughly $350–$1,500 over three years plus a $10–$20 yearly domain renewal. You build it, you maintain it, and you never own the platform. For a brand-new one-person operation, that can be the right call. Say so.
The most expensive over three years is almost always an agency build carrying a monthly retainer, or a large enterprise build: $20,000–$100,000 or more to start, then ongoing on top. Running a professional site alone is $1,000–$17,500 a year (OneLittleWeb), before any retainer. That is how a project quietly becomes a six-figure line over three years.
CDS separates ownership from the operating work. You own the site; the monthly engagement pays for search content, indexation checks, Business Profile work, measurement, and continued improvement. A focused scope starts at $6,000 plus $800 a month, while a complete system commonly plans at $12,500 plus $1,500 a month. The exact workload and quote go in writing.