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E-commerce & Reselling

reseller-arbitrage

Cross-platform reseller arbitrage scanner. Buy Mercari → flip eBay (or any combo). Stealth-browser comp scoring.

Get startedSource on GitHub

Launch kit

reseller-arbitrage — launch kit

1-liner

Cross-platform reseller arbitrage scanner. Buy Mercari → flip eBay (or any combo). Stealth-browser comp scoring.

Tweet hook

Reselling arbitrage: Mercari has 30% lower comps than eBay on certain niches (vintage workwear, lego, watches).

Built a scanner: Mercari listings → eBay comps → margin score → alert.

Operator math: $50 buy → $150 flip × 20/mo = $2K/mo side income 🧵

Reddit

  • r/Flipping: "Cross-platform comp scanner — open"
  • r/Mercari: "Niches where Mercari → eBay arbitrage works in 2026"

Cold-email ICP

Existing flippers active in Mercari/eBay/Poshmark Reddit + Discord.

Cold-email template

Subject: vintage workwear arb — Mercari→eBay

Hi {first} — saw your flipping posts.

Built a comp scanner: pulls Mercari listings, comps against eBay sold
prices, alerts on +30% margin opportunities. Niches I've tested:
vintage workwear, lego, watches, vintage Pyrex.

DIY: free, MIT.
Alerts subscription: $99/mo per niche.

Want to test on your top niche?

SEO content

  1. "Mercari to eBay arbitrage 2026: the niches"
  2. "eBay sold-listings scraping legality + alternatives"
  3. "Flipping ROI: niche-by-niche margin benchmarks"

Documentation

reseller-arbitrage

Cross-platform reseller arbitrage scanner. Buy underpriced on Mercari/Poshmark; resell on eBay where comps are higher. Or any combination. Margin = (eBay sold median × (1 - fees)) - source price - shipping.

Niches that work in 2026

  • Vintage workwear (Carhartt, Pendleton, Filson)
  • Trading cards (specific player rookie cards)
  • LEGO sets (retired sets w/ established sold prices)
  • Specific watch refs (Tudor 1926, Seiko mods)
  • Vintage Pyrex / kitchenware
  • Designer handbags (Coach legacy, Dooney, vintage Gucci)
  • Out-of-print books (cookbooks, niche academics)

Pricing

  • Operator-as-owner $0; you keep all margin
  • Alerts subscription $49-149/mo per niche (we send you opportunities)
  • DFY operation 50/50 split on margin (we run the buying + listing)

Architecture

search_mercari/poshmark   →   listings list
                              │
                              ▼
                     ebay_sold_comps  → median + sold-count
                              │
                              ▼
                            arb.py    → margin / margin_pct / confidence
                              │
                              ▼
                            alerts (CLI today; Telegram/SMS in v1)

v0 ships the scoring; the scrapers are stubs (eBay API requires a free app key + OAuth; Mercari/Poshmark need Playwright with stealth).

Run

cd C:\openclaw-products\reseller-arbitrage
python -m venv .venv
.\.venv\Scripts\activate
pip install -e .

arbscan scan "vintage carhartt jacket" --source mercari --target ebay --min-margin-pct 35

Roadmap

  • Wire eBay Browse + Marketplace Insights (free app key)
  • Playwright scrapers for Mercari + Poshmark
  • Telegram alerts on found opportunities
  • Buy-it-now auto-purchase (with dollar-cap safety)
  • Auto-list on resale platform after purchase + photo