Re processing, grab some RAW data that has been posted on the forums and have a crack at it before you spend a dollar. If you enjoy it, go spend up. If you hate the processing or find it really hard, then sort that out first before you spend a cent. You will spend far more time processing data than catpuring it, so make sure you enjoy that part of the process before parting with any money.
e.g. Download the M27 data from here:
http://www.narrowbandimaging.com/raw...ctice_page.htm
(The other datasets are no longer working, but the M27 raw data is there)
Or here:
http://mistisoftware.com./astronomy/index_fits.htm