You can capture a lot of short exposure frames with standard DS camera and de-rotate them during stacking. Check my
globular clusters images (very amateur
) made with DMK21 and DSI III Pro. The exposures 1-2 sec for DMK and slightly more for DSI III Pro (but it should be longer to get better image depth, but I was limited by bad mount
). With good cameras and focal reducers for SCT you can get short exposures for brighter objects.
Integrating TV/Video cameras anren't cheaper and for imaging they lack resolution -
http://mallincam.tripod.com/id14.html