When I finished my router I bought a Kress spindle to power it, as It's only a small router , 300 x 300 I bought the FM-800 model, 12,000 rpm to 30,000 rpm on a rotary thumb wheel switch. It's controlled by the computer thru one of Roy's breakout boards via the on board relay.

In position 1 to 2 on the control it's bearable close up as regards noise, flat out it sounds like a router.
It has Kress special collets which can be sourced in standard sizes.

I later swapped this for a Chinese air cooled spindle, I had 3 of them before I found a company that sold a reliable unit.
Don't believe all the hype about ceramic bearings, in fact don't go there, one crash and the bearing is toast.

Buying one can be an expensive job, cheap is not always the best.