Different tilt to previous posters:
A distant friend who was hyper dust allergic didn't rate the Dyson machines of the time (~5 years ago) and was especially scornful of the cost. She went to a local hardware shop who fitted her up with a custom-filter vacuum for around two thirds the price, IIRC.
Shops that do that notwithstanding, my best vacuum cleaner has been a bagless Vax upright. Light, powerful, sufficiently well featured, less than half the price. Does a better job than the upright Dyson that preceded it.