I decided to try picking lingonberries for money, just to see how it is. I started in the morning, and after six hours I had this much - I'd guess it is about 50 litres or so. I read that one gets the best price when selling cleaned berries directly to a customer. But lately I've felt even more introvert than usual, the mere though of social interaction feels unpleasant. Also, cleaning the berries would take time, and then more time spent contacting potential customers and delivering or arranging time when they come to pick up. To avoid all of this I preferred to sell directly to a commercial buyer operating at semi-industrial scale - they buy uncleaned berries and pay per weight. They paid me nearly 50 euros, it is tax-free income, so comparing to what an ordinary worker would get after taxes I think 50 € / 6 hours comes close to the low-paid jobs. Surely, not a way to become wealthy, but in my current situation a 50 € helps a lot, so I might try it again later on this autumn.