I started out using a combination of MaximDL and BASS for my spectral processing. Though BASS could do it all I was used to Maxim and so it was easier to use that for dark frames and flat fields to begin with. I find BASS fairly easy to use and intuitive, at least for the basic stuff. Instrument response gets a bit more involved. BASS can be downloaded for free from the astrobodger Yahoo group (don’t be put off by the name!):
Though I still use BASS for my final ‘displaying’ of spectra, I’ve switched to ISIS for all of my processing including dark frams and flat fields. Though it is a lot harder to use, once you’ve got to grips with it, then spectral processing is quick and easy. It automates much of the processing, and so is a lot quicker than the more manual processing in BASS. It is also used by many of the top amateurs which I consider a good indication that it does things right. It can be downloaded for free from Christian Buil’s website:
There are also some tutorials on the site. Though they are quite long I was able to get to grips with ISIS by going through the Lhires III tutorial in detail a couple of times.
I’ll just mention guiding as well, as this is very important for obtaining good spectra. I think there are several good packages out there. I use PHD2, which is free and has built in functionality that is good for spectroscopy. You can setup and adjust a spectrograph slit rectangular guide reticle. You can also nudge the guide location to move the target star exactly over the slit.
On the spectrograph front I think there is going to be something in the next BAA Journal, so I’d suggest holding back until this is published.