Evaluates a major purchase with total cost of ownership, opportunity cost, affordability red lines, and a cooling-off rule, producing a scored buy/wait/walk verdict.
Evaluates a major purchase with total cost of ownership, opportunity cost, affordability red lines, and a cooling-off rule, producing a scored buy/wait/walk verdict. Use when someone asks "should I buy this car", "can I afford this", "is this purchase a good idea", or is about to finance anything with a monthly payment. Do NOT use for fitting an approved purchase into the monthly plan - use budget-builder instead; for whether the purchase should outrank debt payoff or savings - use financial-planner; for home-purchase retirement trade-offs - use retirement-projection.This is the skill's description: the text your AI reads to decide when the skill applies.
big-purchase-decision/SKILL.md
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name: Big Purchase Decision
description: Evaluates a major purchase with total cost of ownership, opportunity cost, affordability red lines, and a cooling-off rule, producing a scored buy/wait/walk verdict. Use when someone asks "should I buy this car", "can I afford this", "is this purchase a good idea", or is about to finance anything with a monthly payment. Do NOT use for fitting an approved purchase into the monthly plan - use budget-builder instead; for whether the purchase should outrank debt payoff or savings - use financial-planner; for home-purchase retirement trade-offs - use retirement-projection.
---
# Big Purchase Decision
Big purchases feel like one-time decisions but are almost always multi-year financial commitments. The costly mistake this skill prevents is deciding on sticker price and monthly payment - the two numbers sellers control - instead of total cost, opportunity cost, and affordability. Analyze before signing, because afterward the analysis is just regret.
## Operating procedure
### Step 1: Confirm the purchase clears the threshold
Apply the full framework to any single purchase above **1% of annual take-home income** (for most households, $500-$1,500). Two lighter rules cover everything below it:
- Below the 1% threshold but still discretionary and unplanned: apply the **24-hour rule** - sleep on it once. Most impulse purchases do not survive one night.
- A useful ceiling for guilt-free discretionary buys: anything under **1% of net worth** rarely warrants analysis for households with positive net worth; above that, it does.
Non-urgent purchases above the 1%-of-income threshold get the **30-day rule**: wait 30 days before buying. Most impulse-driven desires fade within that window; a desire still strong at day 30 that also passes the financial tests below is a considered want, not an impulse.
### Step 2: Gather inputs
1. Purchase price and how it would be paid (cash, financing terms, APR).
2. Annual take-home income and current monthly surplus (from budget-builder if one exists).
3. Ownership costs: insurance change, maintenance, fuel/consumables, registration or subscription fees, expected useful life. Label estimates as estimates.… load the full skill through Skill MeClick to play with sound.