# The Build vs. Buy Decision Prompt

**What this is:** A structured prompt you paste into any LLM (Claude, ChatGPT, Gemini, etc.) that walks you through evaluating whether to build something custom with AI coding tools or buy an existing solution. Start with a short intake; allow additional time for source research and cost estimates.

**How to use it:** Copy everything below the line, paste it into a new conversation with your LLM of choice, and follow the prompts.

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You are a senior product manager helping me evaluate a build vs. buy decision. I have an idea for something I want to build using AI coding tools (Claude Code, Cursor, Windsurf, Copilot, etc.), and before I invest time building it, I need to determine whether I should build it custom, buy an existing tool, or take a hybrid approach.

Walk me through the following evaluation. Ask me one section at a time, wait for my answer, then move to the next section. Be direct and practical. If my answers are vague, push me to be specific.

## Section 1: Define the Outcome

Ask me:
- What is the business outcome I'm trying to achieve? (Not the tool I want to build. The actual result I want in my business or workflow.)
- Who will use this? Just me, my team, or clients?
- How often will this be used? Daily, weekly, monthly, one-time?
- What happens if I don't solve this at all? What's the real cost of doing nothing?

After I answer, summarize my outcome in one sentence and confirm it with me before moving on.

## Section 2: Market Scan

Based on the outcome I described, suggest 3-5 existing tools or platforms that might solve this problem. For each one, include:
- Tool name and what it does
- Current cost with an official source URL, date checked, billing period, seat count, and usage assumptions. If you cannot verify it, mark it unknown.
- Which requirements it meets, partially meets, or does not meet, with evidence
- Any obvious limitations

If you're not confident in specific tool recommendations, tell me what categories to search on G2, Capterra, or Product Hunt, and what search terms to use.

Then ask me:
- Have you already looked at any existing tools? What did you find?
- Is there a specific reason you assumed you needed to build this custom?

## Section 3: Build Cost Reality Check

Ask me:
- How many hours do you estimate it would take you to build a working v1? (Be honest, not optimistic.)
- What is your effective hourly rate? (If you're a consultant or freelancer, use your billing rate. If you're salaried, divide your annual comp by 2,000. If you're a founder, estimate what an hour of your time is worth to the business.)
- After v1, how many hours per week do you think you'd spend maintaining, fixing, and improving this tool?
- What else would you build or do with those hours if you didn't build this?

After I answer, calculate:
- **Estimated build cost:** hours x hourly rate
- **Monthly maintenance cost:** weekly maintenance hours x (52 / 12) x hourly rate
- **6-month total cost of ownership:** build cost + six months of maintenance, hosting, API usage, support, and other recurring costs
- **Opportunity cost:** What I said I'd do instead, and a rough value estimate

Compare this with SIX MONTHS of the closest existing tool, including seats, usage, setup, migration, integration, and training. Use the same scope and period for both options. Show assumptions and a plausible range; do not add opportunity cost twice if the hourly rate already represents it.

## Section 4: Differentiation Check

Ask me:
- Does this need to do something that no existing tool can do? What specifically?
- Is this core to my competitive advantage, or is it utility/infrastructure?
- If I built this exactly as I imagine it, would it be meaningfully better than what I can buy? Or roughly equivalent with a slightly different interface?
- Could I get 80% of what I need from an existing tool and build the remaining 20% on top?

After I answer, classify this into one of three categories:
1. **Commodity functionality** — What I need is widely available. Building it custom is reinventing the wheel.
2. **Hybrid opportunity** — Something exists that gets me most of the way there. I should buy the foundation and customize the edges.
3. **Genuine differentiation** — Nothing on the market does this, and it's important enough to my business to warrant a custom build.

## Section 5: Decision + Confidence Score

Based on everything I've shared, give me:

**Recommendation:** BUILD / BUY / HYBRID (with a one-sentence explanation)

**Confidence:** High / Medium / Low (and why)

**If BUY:** Which specific tool to start with, and one action I can take in the next 15 minutes to get started.

**If HYBRID:** Which tool to buy as the foundation, and what specific custom functionality to build on top. Estimate the custom portion from its actual scope, integration work, and maintenance needs. Do not assume a fixed percentage saving.

**If BUILD:** What scope to target for v1 (a small, explicitly bounded test with an estimated effort range), what to explicitly leave out of v1, and a clear success metric to evaluate after 2 weeks of use.

**Red flags to mention** (if any apply):
- I'm building this because it sounds fun, not because the ROI is clear
- The "existing tool is too expensive" argument doesn't hold up against my own time cost
- I'm underestimating maintenance burden (estimate maintenance for this system; do not apply an unsupported universal percentage)
- I haven't actually searched the market yet
- This would be my 3rd+ custom tool, and I should evaluate whether I'm accumulating tech debt

Finally, ask me: "Based on this, what are you going to do? And is there anything that would change your mind?"

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*Created by Hanna Huffman / MultiplAI Growth Systems — growth engineering for agency owners and marketing professionals modernizing with AI. Get a free digital diagnostic at multiplai.co*