black-friday-deal-detector

Use when evaluating any sale, Black Friday doorbuster, or 'was $X now $Y' claim: detects fake-MSRP anchoring, pre-sale price inflation, coupon-stacking theater, and % off a price nobody paid. Scores the deal against 12-month category price bands and historical-low baselines, with verdicts WAIT / OK DEAL / GREAT / PRICE THEATER.

Overview

The "60% OFF!" tag is theater. Retail's pricing playbook has three moves this skill detects:

1. Fake anchor MSRP — the "list price" nobody has charged for a year. TVs are the canonical case: a 65" TV "listed" at $1,299 that has sold for $799 every non-holiday week since March.
2. Pre-sale inflation — price raised 10–30% in October so November's "40% off" lands at the August price. Trackers catch this; shoppers don't.
3. % off a phantom price — "doorbusters" engineered so the discounted price equals the street price of an equivalent unit, with the delta made up by a made-up anchor.

The math that matters is not % off but price vs the 12-month low band. A "50% off" that lands 5% above the all-time low is a mediocre deal. A "15% off" that undercuts the 12-month low by 10% is a genuinely great one.

This skill scores a claimed deal against category-specific price behavior (TVs depreciate on a curve, Apple gear rarely discounts, mattresses have 400% markups, power tools have two real sale windows/year) and produces a verdict plus a buy strategy.

When to Use

• Evaluating any Black Friday / Cyber Monday / Prime Day / "anniversary sale" claim
• Deciding between two "deals" on similar items
• Checking a doorbuster before queuing or clicking
• Any "was/now" price tag in any store, any month
• Deciding whether to buy now or wait (category seasonality table)

Don't use for: live price tracking (that's price-predator's job with actual trackers), or collectibles with no price history logic.

The Detection Model

Input signals (what you can observe in 60 seconds)

Signal	Where to find it
Claimed list/MSRP	the tag
Sale price	the tag
Street price (major retailers today)	30-second check: Amazon/Walmart/BestBuy/Target
12-month price range	camelcamelcamel (Amazon), Keepa, Honey
Model number + year suffix	the box (e.g., UN65CU7000 vs CX700D)
"Exclusive model" wording	the tag (often a derivative SKU built for the sale)

The seven price-theater patterns

1. Inflated anchor — claimed MSRP > any price charged in 12 months. Score the deal off street price, not MSRP.
2. October bump — price in Sept < price in late Oct < "sale" price. Trackers show it; treat the Sept price as the real anchor.
3. Derivative SKU — model number exists only at this retailer (or differs by one letter). Built to be "exclusive" and un-comparable. Check the spec sheet, not the model name.
4. % off the bundle — discount computed against a bundle whose extras you wouldn't buy (cables, software trials).
5. Coupon-stack maze — needs app + newsletter + card to reach the advertised price. The honest price is the one without the maze.
6. Gift-card-back pricing — "$100 back in gift cards" — real value is 40–70% of face for a store you won't revisit; and it converts the deal into two transactions.
7. Membership-gated floor — the good price requires a paid membership (Costco/My Best Buy+/Walmart+). Fine if you'd pay for it anyway; not a "deal" if the membership was bought for this.

Category baselines (what a real deal looks like)

Category	Typical real discount from street	Notes
TVs	20–35% off street	Derivative SKUs rampant; check panel specs vs model lineage
Apple	5–15% (usually gift-card back)	Real cash discounts rare except clearance/resellers
Laptops	15–30%	Compare CPU gen + RAM + screen, not model name
Mattresses	"50%" is normal pricing	300–400% markup; the real question is coupon-stacked floor
Power tools	20–40%, two windows (June, BF)	Bare-tool bundling hides unit price
Video games	new: 0–10%; catalog: 30–60%	Digital storefronts discount harder than discs for old titles
Small kitchen appliances	30–50% (Ninja/Vitamix/ KitchenAid)	BF is genuinely the low for the year on these
Sneakers/apparel	25–40%	Compare against outlet price, not MSRP
Memory/storage (SSD/RAM)	cyclic 20–40%	Watch for slower-tier component swaps
Toys	30–50% but stock risk	Big-list toys often cheaper in early Dec sales

Scoring

text

real_discount = (street_price − sale_price) / street_price      # vs TODAY's street
anchor_discount = (claimed_msrp − sale_price) / claimed_msrp    # the theater number
low_gap = (sale_price − twelve_month_low) / twelve_month_low    # vs history

• Verdict is driven by real_discount and low_gap, never anchor_discount.
• Any anchor_discount − real_discount > 15 points ⇒ flag PRICE THEATER.

Verdict	Meaning	Action
PRICE THEATER	discount is mostly fake anchor	don't buy; note the street price
WAIT	above 12-month low; category has a better window	set alert at low − 5%
OK DEAL	within ±5% of 12-month low	buy if you need it
GREAT	≤ 12-month low, ideally beating it	buy now; this is the annual floor

Using the Script

bash

# The classic: 65" TV "was $1299", now $799, street today $749
python3 scripts/deal_detector.py --msrp 1299 --sale 799 --street 749 --low 699

# Deal with gift-card back and membership gate
python3 scripts/deal_detector.py --msrp 999 --sale 799 --street 829 --low 779 \
    --gift-card-back 100 --membership-cost 50

# Compare two competing claims
python3 scripts/deal_detector.py --compare "TV-A:1299:799:749:699" "TV-B:1099:749:779:739"

Output: real vs anchor discount, theater gap, gift-card-adjusted price, verdict, and a one-line strategy.

Common Pitfalls

1. Reading the strikethrough price. It is marketing copy, not data. The only numbers that matter: today's street price and the 12-month low.
2. Skipping the model-number check. "Exclusive" derivative SKUs (one letter different) exist precisely so you can't compare. Compare specs.
3. Valuing gift cards at face. $100 back at a store you never revisit is worth maybe $40. Value gift-card-back at 50% unless you shop there monthly.
4. Forgetting return-window resets. BF purchases bought as gifts in November often have return windows that expire Dec 26 — before the gift is given. Check the policy; some retailers extend for holidays.
5. Buying "50% off" mattresses. That's the everyday disguise of the industry; the real deal is the coupon-stacked floor price vs competitors' floor.
6. Confusing clearance with deals. Clearance = discontinued, no support, final sale. Sometimes great; never the same risk profile.

Verification Checklist

• Street price checked at 2+ major retailers (not just the seller)
• 12-month low pulled from a price tracker (camelcamelcamel/Keepa)
• Model number matches the comparable unit (letter-suffix check)
• Gift cards valued at 50%, membership cost amortized in
• Verdict from real_discount + low_gap, not the anchor