A hat against the sun ( 30 € ). It makes me want to go out more because I feel so much better when the sun doesn't burn my head. I should have tried this earlier in my life. It is also better to have shade on my face through the hat than to wear sunglasses which make the colours look weird and were expensive because I needed a subscription.
A good kitchen knife and a sharpening stone (€80 knife / €15 stone). Makes cooking so much better.
A hand fan. ( 3 € ) At first it was strange to use one, because in Germany they don't use them like in Spain for example. It is light, fits in my pocket, I can use it anywhere, it does not need batteries and everyone who tries mine buys one afterwards.