Record the full landed cost
Purchase price is only the beginning. Add buyer protection, shipping, cleaning, repairs and any direct preparation cost to understand the true entry point.
Set a target before listing
Estimate marketplace fees, tax and expected negotiation room before choosing a selling price. This gives every item a visible margin target instead of a hopeful markup.
Watch age as closely as margin
High theoretical profit can disappear if capital sits in slow stock. Review aging inventory by category and decide whether to relist, reprice, bundle or exit.
Use data to improve the next monitor
Your inventory history should feed back into sourcing. Raise or lower price ceilings, prioritize faster brands and retire searches that create work without reliable sell-through.