Hey David,
you can also start with a cheap compressor from the hardware store. They deliver easily more air flow and pressure and start at $150. They are just loud. You will pay more if you want an extremely quiet one, as the ones I mentioned in my post from the other day (45 dB). They are very expensive but do you know how silent 45 dB is? It’s considered as silence. It’s the noise that your refrigerator makes. A conversation between to persons in a room is already 60 dB.
Another solution to avoid brass dust, which cannot be extracted like wood dust easily, entering the spindle (and everything else like ball screws, linear bearing etc.) and damaging it, is to use a cutting fluid. Brass can be cut without, but all metals benefit of it when milled. But of course that is not compatible with MDF wasteboards 
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