My wife buys and resells stuff from car boot sales, charity shops, and flea markets. A few months ago I started building her a free iOS app to track it all — FlipperHelper. It's on about 70 downloads now, no revenue, no ads. The biggest feature request I kept getting was some way to answer a simple question: was that sourcing trip actually worth it? The problem When you go to a market you spend money in a lot of different ways. Entry fees, fuel or train tickets, maybe parking. Then you buy items — sometimes 5, sometimes 20. Some sell within a week, some sit for months. The expenses and the items live in completely different timelines. By the time the last item sells, you've forgotten what you even spent on that trip. My wife was trying to track this in a spreadsheet and it was a nightmare to maintain. What I built The feature is called Hauls. You create one, pick the dates of the trip, and the app shows all the items you bought in that period. You select which ones belong to this trip.…