Buy off-the-shelf if your process looks like everybody else's; build custom when the shape of your operation is the point. For most UK service businesses that means starting on a £25–£150 per-user CRM. Building only pays when a product would force you to work in a way that costs you money — and a build starts around £7,000, not the £10,000–£30,000 you will be quoted elsewhere.
We are an unusual place to get this answer, because we sell both. TenureBook is our off-the-shelf product, at £295 a month. A Proprietary Database is our bespoke build, at £7,000 plus £100 a month. We make money either way, so we have no reason to push you toward the expensive one — and we regularly tell people to stay on the software they already have.
The honest comparison
| Off-the-shelf CRM | Custom build | |
|---|---|---|
| Cost to start | £25–£150 per user per month | £7,000+ one-off (UK market typically quotes £10,000–£30,000) |
| Ongoing | The subscription, rising with seats and tier | Hosting and support — ours is £100/month; the industry benchmark is 15–25% of build cost a year |
| Live in | Days | Weeks |
| Fit | You adapt to the software | The software matches how you already work |
| Ceiling | Features you need sit on a higher tier, or do not exist | Whatever you are willing to pay to build |
| Risk | Low. Cancel and leave | Real. A bad build is money gone |
| Ownership | You rent it. Prices and terms can change | It is yours, and it stops being a line item that grows |
When you should NOT build
We say this first because it is the answer more often than the industry admits:
- Your process is normal. Leads, quotes, jobs, invoices, follow-ups. Every CRM on the market does that, and does it well.
- You are under about £500 a month on software. At that level the arithmetic simply does not favour a build.
- You have not yet written down how you work. A build makes your process permanent. If it is still changing weekly, freeze it in a spreadsheet first, not in code.
- Nobody internally owns it. Custom software with no owner rots exactly as fast as a spreadsheet with no owner.
- You want it because the off-the-shelf one is annoying. Annoying is not the same as expensive. Price the annoyance in hours before you price a build.
When building genuinely pays
- Your work does not fit the CRM shape. CRMs assume a contact, a deal and a close. If the thing you actually track is a property, a lease, a case, a fleet or a job with sub-jobs, you spend your life bending fields that were named for something else.
- You are paying for seats that barely use it. Per-user pricing punishes teams where ten people need to look and two need to edit.
- The feature you need is one tier up — permanently. Reporting, automation and API access are the classic upsell wall; the jump from £25 to £150 a user is where a build starts paying for itself.
- Your data lives in five places. The value is usually not a better CRM, it is one set of records everything else reads from.
- The manual work is measurable. If someone loses two hours a day to retyping between systems, that is roughly ten working weeks a year — and it is the clearest build case there is.
The arithmetic, honestly
Take a team of eight on a mid-tier CRM at £60 per user per month. That is £480 a month, £5,760 a year, rising every time you add someone or need a feature from the tier above. A £7,000 build with £100 a month running costs is £8,200 in year one and £1,200 a year after that.
On those numbers the build crosses over in about year two — and after that the gap widens every year, because your cost stops scaling with headcount. But that comparison is only honest if the off-the-shelf option genuinely does not fit. If it fits, the subscription is the cheaper answer for as long as you use it, and we will say so.
The middle option most people miss
Build-or-buy is a false binary. There is a third answer: a ready-made product built for your specific industry. It costs like software, not like a build, but it already speaks your language.
That is exactly what TenureBook is for property portfolios — every occupier, lease, key date and figure in one book, from £295 a month, live within a minute of checkout. No generic CRM tracks a break-notice deadline. No build was needed either. If a product like that exists for your sector, it usually beats both options.
What we actually did, and what it cost
Our first client was a UK commercial-property firm running a portfolio out of spreadsheets. A CRM was the wrong shape entirely: the thing they needed to track was not a deal, it was a lease with dates attached that cost real money when missed. So we built them a Proprietary Database — companies, properties, leases, financials, documents and reminders in one system. They run on it every day.
That build then taught us the product. The lessons became TenureBook, which is why we can say with a straight face that the off-the-shelf answer is often right: we made one. The full breakdown of what a bespoke build includes and costs is on the Proprietary Database page.
How to decide this week
- Write down the five things your team does most, in order.
- For each, note whether your current software helps, tolerates it, or fights it.
- Count the hours a week lost to the ones it fights, and multiply by what an hour is worth.
- Compare that to £7,000. If it is not close, stay where you are.
If you want a second opinion from someone who sells both answers, book a short call — we will tell you honestly which one fits, including when the answer is "keep what you have". Or send us the details and we will come back with a fixed quote.