You did the sensible thing. You asked three companies for a price. And then three numbers arrived that were so far apart you began to suspect that at least two of them were making it up.
That reaction is correct, in a way. But the reason is not usually dishonesty. It is that the three quotes were not describing the same work at all, and nobody told you that.
I am not going to give you an average figure in this article, and I want to explain why before we go further. Every published "average cost of SEO" number you will find online comes from a survey of agencies, promoting agencies, and it tells you almost nothing about what is right for a heating company in your particular city. We do not publish estimated numbers, because an invented figure that sounds authoritative is worse than no figure at all. What I can give you is something more useful: exactly what drives the price, and how to judge whether a quote is fair.
In short: four things move the number, which are your market's competitiveness, how many services and areas you want to win, the state of your website now, and whether you are buying a fixed project or an ongoing arrangement. Force every quote onto the same list of deliverables and the comparison becomes simple. If a quote cannot be described in nouns, it is not a quote, it is a subscription.
Why trades pricing is different from other businesses
Plumbing and heating have a particular shape that changes the maths.
Your customers are often in trouble. A burst pipe at eleven at night, a boiler that failed on the coldest weekend of the year. That person is not researching carefully. They are looking at a phone, at whoever appears first, with whatever rating is visible, and they are calling within about ninety seconds. We wrote about that specific moment in marketing for plumbers when the pipe bursts.
This means two things for your budget. First, the map results and your Google Business Profile matter enormously, often more than the website itself. Second, the value of a single job can be substantial, and an installation can be very substantial, so the arithmetic of what a customer is worth is quite different from a shop selling small items.
That second point is the one owners forget when they look at a quote and flinch. The right question is never "is this a lot of money". It is "how many jobs does this need to produce before it has paid for itself, and is that number believable".
The four things that actually set the price
How competitive your city is. Getting found for heating repair in a large city with forty established companies, several of them spending heavily, is a different job to the same thing in a town with four. It is not slightly different. It can be several times the work. Any quote given before somebody has looked at who you are competing with is a number pulled from the air.
How many services and areas you want. Being found for one thing in one town is a small project. Being found for boiler repair, boiler installation, emergency callouts, servicing contracts and underfloor heating, across six surrounding towns, is thirty pages of genuine work. Each of those pages must be real and distinct, or you create the doorway page problem we describe in service area pages without a doorway penalty.
The condition of what you have now. A site that is technically sound with thin content needs writing. A site that is slow, unmaintained and invisible to search engines needs repair before any writing is worth doing. These are very different bills, and the only way to know which one you are is to have somebody look.
Project or ongoing. A fixed piece of work to correct the foundations has an end. An ongoing arrangement does not. Both can be reasonable. Only one of them stops.
The six questions that tell you if a quote is fair
Take every quote you have received and ask the same six questions. This is the whole method, and it works even if you know nothing about search.
What will exist in ninety days that does not exist today? You want an answer made of nouns. Twelve service pages. A completed profile. A fixed sitemap. Fifteen new reviews. If the answer is made of verbs and adjectives, "we will optimise and enhance your presence", you have learned something important.
Which searches are we going after, exactly? They should be able to show you a list, and the list should contain the words your customers use, not industry vocabulary. "Emergency plumber Croydon" is a target. "Increased visibility" is not.
Who does the work, and where? Not who sold it to you. The person who will write your boiler installation page should ideally have written a page about something physical before.
What do I own if I leave? Your website, your content, your Google account, your reviews, your domain. All of it should be yours already, and you should be able to walk away with everything. If the answer is complicated, that is your answer.
How will we measure this in terms I care about? Calls, booked jobs, quote requests. Not impressions. If you want the honest list of what to track, we set it out in how to measure SEO return.
What is the cheapest thing on this list, and can I do it myself? A confident provider will tell you. Usually the answer is your Google Business Profile and your reviews, and a good one will happily explain that you should do that first regardless of whether you hire them.
The thing that costs nothing and matters most
I want to be direct about this because it will save you money.
Before you spend anything with anybody, complete your Google Business Profile properly. Every field. Correct hours including the emergency ones. Real photographs of your vans, your team, your work, not stock images of a smiling person holding a wrench. Every service listed. Service areas set correctly.
Then build a review habit. Not a campaign, a habit. Every completed job, a short message asking for a review, sent the same day while the relief is fresh. This one practice moves more emergency calls than most paid work does, and we wrote the practical version in how to get more Google reviews.
If a company quotes you a large monthly figure and has not mentioned either of these, be careful. They are selling you the expensive part before the free part.
When to spend, and when to wait
Spend when you have a specific gap you can name: you do not appear for a service you make good money on, or you are invisible in a town you can easily reach, or your site is broken in a way that stops people calling.
Wait when you cannot yet name the gap. Money spent without a specific target is how owners end up paying for twelve months of activity and cannot say what changed.
And if you are not sure which situation you are in, find out before you buy. Our free visibility check tells you which searches you currently appear for, what your profile looks like to a customer, and what is missing, in ordinary language. Take that report into your three quotes and you will negotiate from facts instead of from worry.
The honest summary
The right price for your business is the price of a defined list of work that closes a gap you can name, from somebody who can tell you what will exist when they are finished.
Judged that way, a higher quote is often the cheaper one, because it is the only one that actually includes building the pages you are missing. And the lowest quote is frequently the most expensive thing in the world: a small amount of money, every month, forever, for nothing you can point at.