Find genuinely comparable items
Match model, size, edition, included accessories and condition. Look for completed sales where available and check whether the final accepted price is actually visible. Separate bundles, damaged examples and unusually rare variations. Record the date and channel because markets change.
Account for the full buyer cost
A low item price with high shipping is not directly comparable to a shipping-included listing. Consider taxes, shipping and return terms when thinking about customer choices. Do not assume a seller's fee structure matches yours or use someone else's claimed profit as your own estimate.
Choose a range and a floor
Use a realistic range of comparable outcomes rather than an isolated outlier. Calculate the price required to cover your costs and your own target margin. That floor is a planning constraint; it does not make an item worth that amount. Sometimes the correct decision is not to buy.
Revisit stale listings
If an item does not sell, first review accuracy, photos, category and price. Decide whether to lower the price, change the channel or stop tying up space. Include the cost of returns and unsold inventory in your broader records. A successful sale of one item is not a forecast for a category.
What if there are no comparable sold items?
Treat the uncertainty as a reason to reduce exposure or pass. Research related models carefully without pretending they are exact substitutes. An absence of listings can mean rarity, weak demand or poor search terms; it does not establish a high resale value.