Build vs Buy ROI

Should you build custom software or buy an off-the-shelf solution? The answer depends on ROI. Custom is usually more expensive upfront but cheaper over time if it delivers unique value. Off-the-shelf is cheaper initially but more expensive if you heavily customize it. Understanding the true cost of each path is critical.

The True Cost of SaaS Over 5 Years

Let's say you need a project management tool. You consider buying Asana vs. building custom.

Asana cost (100 users, 5 years):

— Seat cost: $12.50 per user per month (Team plan)

— 100 users × $12.50 × 12 months × 5 years = $750,000

— Implementation and training: $10,000

— Custom integrations (2 at $5,000 each): $10,000

— Data migration and cleanup: $5,000

— Annual admin overhead (0.5 FTE at $75k salary): $375,000

Total 5-year cost: $1,150,000

That's expensive. But wait—does Asana solve 100% of your needs? Probably not. You need custom fields, custom workflows, integrations with your other systems. You end up hiring someone to manage Asana and build workflows. That person is overhead that doesn't exist if you buy simpler software.

The True Cost of Custom Build Over 5 Years

Custom project management tool (100 users, 5 years):

— Initial development: $150,000

— Year 1–5 maintenance and features (10 developers × $150,000 salary × 0.2 allocation): $150,000 per year × 5 = $750,000

— Hosting and infrastructure (growing from $1,000–$10,000/month): $150,000 total

— One full-time PM/ops person to manage the tool: $75,000 × 5 = $375,000

Total 5-year cost: $1,425,000

Hmm, that's more than Asana! But wait—you own the software. You control it. After 5 years, you still have a working tool that costs you $20,000 per year to maintain (instead of $750,000 to buy + overhead). The ROI turns positive in year 6.

The ROI Framework: Break-Even Analysis

Compare cumulative costs over time. At some point, the custom build becomes cheaper than SaaS.

Example: Project Management Tool

Year 0 (Build): Custom $150k, SaaS $0

Year 1: Custom $150k + $150k maintenance = $300k cumulative, SaaS $150k × 100 = $150k

Year 2: Custom $300k + $150k = $450k, SaaS $150k + $150k = $300k

Year 3: Custom $600k, SaaS $450k

Year 4: Custom $750k, SaaS $600k

Year 5: Custom $900k, SaaS $750k

Year 6: Custom $1.05M, SaaS $900k

Year 7: Custom $1.2M, SaaS $1.05M (break-even!)

At year 7, the custom build is worth the investment. Year 8+, you save money every year vs. SaaS.

When Custom Wins: Unique Advantage

Unique competitive advantage: If custom software gives you competitive edge that no SaaS can match, it might be worth the investment. Example: Netflix's recommendation algorithm is custom and proprietary. That's millions in R&D because it drives user retention and revenue.

Doesn't fit any existing tool: Sometimes you have unique needs that no SaaS addresses. You need custom workflows, unique data models, or industry-specific features. Building custom is the only path.

High user count makes per-seat SaaS expensive: If you have 500 users and pay per seat, that's $100,000–$250,000+ per year just for seats. Build custom once, scale to unlimited users for minimal incremental cost.

You need to own the data and IP: With SaaS, your data lives on someone else's servers. With custom, you own it. If data privacy or IP ownership is critical, custom wins.

Integration is complex: If you need to deeply integrate the tool with 5+ other systems, the integration cost with SaaS can rival building custom. Building custom lets you own the entire data flow.

When SaaS Wins: Commodity Functionality

Commodity functionality: Email, payments, CRM, HR systems—these are solved problems. A SaaS like HubSpot or Salesforce is mature, trusted, and industry standard. Custom is overkill.

Limited budget: If you can't afford $100,000+ upfront, you can't afford custom. SaaS lets you pay as you go.

Speed to market: You can have a SaaS up and running in days. Custom takes months. If your market window is short, SaaS is the answer.

Low user count: With 10–20 users, per-seat SaaS is cheap. Building custom makes no sense economically.

Maintenance burden: You don't want to maintain software. Let Salesforce handle updates and security. You focus on your business.

The Hidden Cost of Customizing SaaS

You can have your cake and eat it too, right? Buy Salesforce and customize it to your needs?

Be careful. Customizing SaaS is a trap. Every customization:

— Costs $5,000–$50,000 per custom feature

— Creates maintenance burden when the SaaS updates

— Often requires hiring specialists (Salesforce Apex developers, for example)

— Locks you in (switching to another SaaS requires rebuilding your customizations)

You end up with custom software built on top of SaaS. You have the downsides of both: ongoing costs of SaaS + development costs of custom. The worst of both worlds.

Common example: companies spend $500,000 on Salesforce + $300,000 on customizations. They could have built a simpler custom CRM for less and owned it completely.

A Worked Example: Accounting Software

You need accounting software for your business. Xero costs $70/month per company. QuickBooks costs $50–$200/month per company. Both are mature, trusted products.

Building custom accounting software would cost $300,000+. You have 10 accountants using it. Break-even is: ($300,000 + $60,000/year maintenance) ÷ ($70 × 12 × 10 users) ≈ 4.3 years.

Unless your needs are unique (custom tax rules, complex consolidation, integration with legacy systems), you should buy Xero or QuickBooks. They're cheaper, proven, and you don't have to maintain them.

Now, if you have 100 accountants, the SaaS cost jumps to $84,000/year. Custom becomes attractive at that scale.

Decision Framework: Build vs. Buy

Ask yourself:

1. Is there a good SaaS solution that does 80%+ of what I need?

2. Can I afford SaaS for 5+ years ($100k–$500k)?

3. How many users will I have in 3 years? (If >100, custom might be cheaper per user)

4. Is this core to my business or competitive advantage? (If yes, custom might be worth it)

5. Do I have 6+ months to build custom? (If no, buy SaaS)

6. Will I need to customize the SaaS heavily? (If yes, calculate customization cost; it might rival building custom)

If most answers point to "buy," buy. If most point to "build," build. If it's mixed, lean toward SaaS unless you have strong reasons to build.

Build vs Buy Comparison

Hybrid: API-First SaaS + Custom Layer

A middle ground exists: use SaaS for the commodity parts and build custom on top.

Example: use Stripe for payments (don't build payment processing—it's complex and regulated). Use Auth0 for authentication (don't build login; security is hard). Build your custom app on top of these services via APIs.

This gives you: speed to market (using SaaS services), cost efficiency (you pay only for what you use), and flexibility (your app is custom).

This is often the best of both worlds, if you have the technical expertise to integrate APIs properly.