In the 1980s I invented the ????? and got £2000 from a large British Company in full and final settlement. The invention is used throughout the world today and I am still known locally as the man who invented the 'thing'. £2000 for a moment of inspiration followed by a letter seemed amazing at the time.
A few years earlier when digital goods started to appear, I had a similar good idea and sent it to Ingersol a large watch making concern which may still be on the go. Their reply stated that they might never use the idea but by way of thanks for sending it to them they also sent their catalogue inviting me to choose a watch. Naturally I chose the most expensive one. The idea itself was so simple and suggested an ad which went along the lines of, "10.59, is that the time? No, that's the price!"