I like many different styles and brands of vacs, and although I like Dyson's earlier models up to about 2006, after this I don't own one, as I feel they are still too expensive for what they are.
Kirby is not even competing with Dyson, and they are 2 very different vac designs, so there is no comparison. Kirby has always been a traditional vac and its timeless classic design still sells to Kirby fans. I like to call it the Harley Davidson of Vacuums - all chrome and classic styling.
Dyson is more the Ford Focus of vacuums - very popular, and purchased by all and sundry that want the latest in design and to fit in with the crowd. You could say that Dysons are a fashion accessory.
Kirbys are designed to last a very long time and are built to a high standard in the USA, whereas Dysons are made in the Far East, and mass produced to be thrown away when they break down and the warranty has expired. That's where the difference in price comes from. The Kirby is built to the quality of Pre-1980's vacs and in those days, relative to earnings, a Hoover Senior would have cost todays equivalent of £600 ie, they were a luxury item and only the well off could afford one, with most Hoover customers going for the cheaper Junior model.
Dysons are so expensive because people are prepared to pay the high prices (£400 for a DC41). If no-one bought them for the current prices, then Mr Dyson would either go bust, or have to lower prices till people bought his vacs.