David
(warning...very non-expert advice follows
)
Have you considered a Philips ToUCam Pro II? You need to unscrew the lens and insert an adaptor (available on the web) and when linked with some great free software (K3CCDtools & Registax) makes an excellent planetary imager...something to do with a CCD chip over a cmos chip I think. I'm only a recent ToUcam owner, but I am certainly impressed. If you are on the southside of Brisbane, we could organise a meetup and your welcome to try it out before you buy.