A simple way to track LEGO investing sets before the spreadsheet gets messy

One thing I’m noticing with LEGO investing is that tracking becomes messy faster than expected. At the beginning, a simple spreadsheet is enough. But once you have more sets, different buy prices, storage, resale fees, and multiple marketplaces, it becomes harder to know if a set is actually performing well. A simple tracking structure I’m testing: Set name + set number Buy price + quantity Estimated current resale price Minimum sell price target The most useful number is not just “current...