For cheap guiding this could work:
http://www.ebay.com/itm/Point-Grey-R...-/290761823982 - but you are limited with ~0,5sec exposures and not so high gain.
For cheap primary camera for a SCT you could check Brightstar Mammut with ICX429 CCD (cooled). As it's only 1/2" diagonal it can also work with f/3.3 SCT reducers.