What’s a realistic yearly maintenance / version-upgrade cost?

Per extension, the realistic yearly maintenance cost is the support-renewal fee + the dev hours to validate it after each Magento upgrade. Concrete numbers from my client data:

• Mid-market paid extension ($500 license): $150-$250/yr support renewal + ~2 dev hours per Magento minor upgrade ($150-$300). Total: ~$300-$550/yr.
• Enterprise paid extension ($2,000 license): $600-$1,000/yr support + 4-8 dev hours per minor ($350-$1,200). Total: ~$1,000-$2,200/yr.
• SaaS extension ($50/mo license): $600/yr license + 1 dev hour per Magento minor ($120). Total: ~$720/yr.
• Free open-source extension: $0 license + 4-12 dev hours per minor ($350-$1,800), because you own the maintenance.

Stacked across a typical mid-market store with 12-18 paid extensions, you’re looking at $3,000-$8,000/yr in extension maintenance, separate from your storefront dev retainer. Surprises that bust this budget:

• A Magento minor that breaks 3-4 extensions at once (happens every 18-24 months).
• A vendor end-of-life&rsquo ing a module — ripping out + replacing is 8-30 dev hours.
• A security disclosure forcing an emergency patch + retest cycle.

Plan for it — it’s not optional.