There's a moment in many companies' lifecycles when they realise their "SaaS subscription" actually involves $80k/year of custom development consulting on top of $40k/year of licensing — and they think this is somehow different from building custom software. It isn't. It's custom software, built on someone else's platform, paid for at premium rates, with all the downsides of vendor lock-in.
Here's the honest math.
The pattern
It usually goes like this:
- Year 1: Adopt Salesforce / HubSpot / NetSuite. Standard pricing, light customisation.
- Year 2: First custom field, first custom workflow, first custom report. Maybe $5k/year in consulting fees.
- Year 3: Workflow gets more complex. Three or four custom apps built on the platform. $20k/year in consulting.
- Year 4: Custom Apex / Lightning / SuiteScript. $50k/year in consulting.
- Year 5: You realise you have a custom application that happens to live inside Salesforce. $80–120k/year in licensing + consulting combined.
What you've actually built
By year 5, you've built custom software. The reality:
- 60–80% of the functionality is in custom code you (or your consultants) wrote
- 20–40% is core SaaS functionality you genuinely use
- 100% is locked inside the SaaS vendor's platform
If you exported the system today, you'd have nothing portable. The custom code requires the vendor's platform. The data is in their schema. The workflows assume their UI.
The cost comparison
Year 5 of heavy SaaS customisation vs year 5 of native custom build:
Heavy SaaS customisation path
- Year 5 SaaS licensing: $80–150k/year
- Year 5 customisation consulting: $40–100k/year
- 5-year cumulative: $400k–1M+
- Ownership: zero
- Exit story: rebuild from scratch
Native custom build path
- Year 1 build: $80–180k one-time
- Year 2–5 maintenance: $30–60k/year × 4 = $120–240k
- 5-year cumulative: $200–420k
- Ownership: complete
- Exit story: continue running, no vendor
Why this happens
Three reasons companies end up in heavy SaaS customisation rather than native custom:
- Sunk cost. "We've already paid for Salesforce licensing, might as well build on top."
- Procurement friction. Adding a custom dev contract is hard. Adding more SaaS consulting hours is easy (existing vendor).
- Optical preference. "We use Salesforce" sounds better to investors than "we built custom software."
None of these are good reasons. The math favours native custom by year 3–4 in almost every case.
When SaaS customisation is genuinely OK
Light customisation (5–10% of standard SaaS work) on top of a 60–80% standard SaaS usage pattern — totally fine. Add a couple custom fields, write a few Zapier flows, build one or two simple apps.
The line gets crossed when:
- Customisation consulting exceeds 50% of licensing fees
- You have a dedicated "Salesforce developer" or equivalent
- You've built more than 3–4 substantial custom apps on the platform
- The custom code is no longer documented because the consultant turned over
The replatform decision
Once you're in heavy customisation territory, the question becomes "when to replatform to native custom."
The replatform decision is easier when:
- Annual SaaS+consulting exceeds $150k/year
- The custom code is documented and the team understands it
- The business is stable enough to invest in a 6–12 month migration
- Vendor pricing or strategy has changed materially against your interests
If you're considering this move, see our NetSuite migration playbook — the principles apply to migrating off any heavily-customised SaaS.
For a transparent cost comparison for your specific scope, our cost calculator runs 5 questions. Or contact us for a 48-hour scope.