We build marketplace apps for a living, including our own, so we see the budgets people arrive with and the invoices they leave with. The gap is usually not incompetence on anyone's part. It is that a marketplace app has four cost centers and most quotes only price two of them.
The four cost centers
One: the integration itself - OAuth flow, webhook handlers, the actual feature. Two: the marketplace review - listing requirements, security questions, the review cycles where HighLevel asks for changes. Three: multi-tenant infrastructure - your app runs for every location that installs it, simultaneously. Four: maintenance - the platform API evolves and your app has to keep up.
A quote that only covers center one is not a smaller quote. It is an unfinished app.
Real ranges
A thin app - one direction of data sync, no UI inside HighLevel - lands in the low five figures when built properly with review handling included. A real product with embedded UI, billing and multi-channel logic is a mid five-figure build over two to three months.
The variable that moves price most is not features. It is how many external systems the app talks to and how badly each of them handles rate limits.
The maintenance line item
Budget 10 to 15 percent of build cost per year. API versions change, webhook payloads grow new fields, review policies tighten. An unmaintained marketplace app does not stay still - it degrades.
If your developer disappears after launch, this is the bill that finds you. Ask about maintenance before you sign, not after the first breaking change.
Key takeaways
- Four cost centers: integration, review, multi-tenant infra, maintenance
- Review cycles and multi-tenancy are where cheap quotes fall apart
- Budget 10-15 percent of build cost per year for maintenance
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