A dust collector won't do much for a ROS, unless you build a sanding table,
and you would have to devote an eighth of your shop to it. You can attach a
shop vac to the dust port (if your ROS has one), and it works pretty well,
but is a PITA.

IMHO DCs are overrated. They only work well on tools that are, or can be,
completely enclosed. I recommend, at least for a first tool, a good air
filter. The heavy dust will fall to the floor, and the air filter will
clean up the fine dust. Supposedly a big enough DC will work in open
applications, but my 1.5hp won't.

Incidently, my 1.5hp has a 1micron bag and is very clean. Reportedly the
30micron bags collect the coarse stuff that doesn't much matter and makes an
aerosol of the finer stuff; probably worse than doing nothing.

Boy, four acronyms in one posting!