Hi Michael,
to IceInSpace!
I'm using a DMK21AF04 for autoguiding, because I already had it for use with my planetary imaging. The DMK21AF04.AS (new versions) can do exposures up to 60 minutes, so 1-2s exposures or less, for auto-guiding, is no big deal.
You can use a ToUcam 900nc, unmodified, as long as your guide star is bright enough - because it can only do as long as 1/25s exposure.
Most people either modify the ToUcam to be able to do long exposures, or you can get something like a 2nd hand LPI or DSI which will do the job well.