I'm trying to think what I've invested in...
From gliding, I have sunglasses (about my 10th pair at the rate i break them), a hat, a cheap digital wristwatch, a chart, some pens for the chart, a ruler marked in nautical miles, a glider pilot's licence, and an FRTOL.
Since starting my NPPL, so far I have invested in a logbook, an A5 clipboard, some Pooley's books and an Air Quiz subscription.
This collection of items lives in an old rucksack along with old food wrappers, gloves and half-used bottles of suncream.