Hank,
I used to run a Kress 800 with the speed knob set to 1 or 2 and it wasn't bad, not ER11's but collets are available. Above 1 or 2 it does get noisy.
Then got one of the air cooled spindles from ARC and run this at 200 hz which is 12,000 for most things, quite quiet, at full speed it's about the same as the Kress on 2.

I believe the water cooled ones are quieter as they don't need a fan but depending on who you buy from in China there is some right rubbish. When we were looking at the air cooled units we wrecked a few until we found a supplier who had inside the unit what they said they had.

The unit from the Stateside looks interesting but only for light work.

For light work the spindles that people are making out of the RC outrunner motors look very interesting, someone was doing a project log on them last month, forget who.

[EDIT] Jonathan got the links into to the brushless motors whilst i was typing.