I recently wanted to buy a second hand laptop and checked different websites. Every seller quotes something different and I had no idea what the right price was. The bigger worry is what if it works fine for a couple of days and then starts lagging. You pay, you hope and sometimes you regret. A tool that checks the device model, year, current performance, speed, charging health, physical damages and gives a fair price before you buy would fix this completely. For laptops, mobiles, cameras, everything.