I think Dyson benefits from the same effect as Apple/Tesla/Beats/etc. Their products are good but their triumph is upselling. Dyson cordless vacuums are like $800+, was your previous one that expensive?
Their tech can probably be imitated at a lower cost, but I won't take chances with the cheaper knockoffs, the tradeoff is not worth it.
I should add that I called Dyson once for my 7 year old wireless vacuum which was having battery problems. They mailed me a replacement completely free of charge. The upselling might be there, but the up-service also seems to be there.