Guides for people who buy to resell

Short guides with worked examples. Every example number is checked against the free tools, so you can reproduce it.

• How to calculate resale profit, ROI and margin

  Profit, return on cost and margin are three different numbers. A worked example you can check.

• UPC, EAN and GTIN: what the barcode numbers mean

  What the numbers mean, how the check digit works, and what to try when a barcode search finds nothing.

• Break-even and the most you can pay for an item

  Work backwards from the price you expect to sell at to the most you can pay.

• Why total cost beats sticker price when you source

  The lowest price tag is not always the lowest cost. Compare stores by price plus shipping.

• What to look for in a barcode scanner app for reselling

  A checklist for comparing scanner apps: formats, what they show after the scan, speed and cost.

• The costs that quietly shrink your resale profit

  Fees, shipping both ways, supplies and returns. A worked example of how a wide gap becomes a thin profit.

• Asking price vs sold price: which one to trust

  A listed price is a hope and a sold price is a fact. How to tell them apart when you estimate resale value.