Reselling Second-Hand Goods: Maximum Buy Price, Fees, Days to Sell, Inventory Ageing, Lot Buying & Profit per Hour

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Work backwards from what an item will sell for: fees, shipping and packaging come off, a target profit with a minimum is kept, and the rest – rounded down – is the most Nadia may pay at the market.
• Add up the full fee stack of four fictional sales channels for one item – sales fee, payment fee, fixed fees and whether the fee also applies to shipping – and find where Nadia keeps the most.
• Turn a simple log of bought, listed and sold dates into days to list, days to sell, the share of items that sold within 30 days and a count of listings that have gone stale.
• Give every unsold item its age, sort it into an age bucket with IFS, apply a markdown rule from a small table and find how much of Nadia's money is stuck in stock older than 60 days.
• Spread the price of a mixed box over its items by estimated value, see which items really carry the profit and work out the most Nadia could have paid for the whole box.
• Add up the minutes spent sourcing, cleaning, photographing and packing each item, turn profit into profit per hour, pool it for the week and count the items that fall short of Nadia's target rate.
• Take a month of sales by category, subtract the cost of returns and of items written off, and measure the return rate and how many margin points returns and write-offs cost.
• Summarise a month of sales by sourcing channel with SUMIFS and AVERAGEIFS, answer a two-condition question and chart the profit by source so Nadia knows where to go hunting next month.