cheap dust collection solution?

[Jonathan]

Wrote this then realised I completely missed the point. There are plenty of readily available designs for making a cyclone, so I'd just do that.

[It's difficult to get standard vacuum cleaners to work for dust extraction because the flow rate is quite low, particularly compared to the 'proper' dust extractors. If you can enclose the cutter sufficiently well it could work, but if not the problem is the dust is expelled at such a high speed that (without any barrier to stop it) it will not be caught by the vacuum.

I have one similar to this:
Clarke CDE35B Dust Collector - Machine Mart

The flow rate for that is several times that which you can get with a standard vacuum cleaner. It can be improved by making a cyclone to accumulate the dust, which is simple enough.]