In article ,
Broadback writes:
How can you call Dyson filters relatively cheap?

You never have to replace them (at least I never have).

they clog almost immediately with plaster, cement dust etc.

Not in my experience, indeed a Dyson is the only thing I've
found that actually copes with these. I can normally get 5
or more large canisters full of plaster/cement dust before
swapping a filter. Each canister holds many times the
capacity of a vacuum cleaner bag in any case. I wish someone
made an industrial grade portable cyclone cleaner which came
close, but they don't (and can't because Dyson holds all the
patents on making small cyclones viable).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]