Egregoros

@eee It's a little more expensive than the 6D, but I think the Sony Alpha a7S is one of the best low light cameras you can get for the money today. They can be found on Ebay for around 400~600 dollars used with a very low shutter count because it's primarily a video camera.

The big advantage with them is that they have very big pixels. It's a 12MP camera, so it's "low resolution", but this is an advantage for astrophotography. The major one is that bigger pixels are more forgiving for less than perfect tracking (or even no tracking).

The other reason that they are good is that it's possible to remove the IR filter on these. I was told you can't do this with the a7sII and a7sIII, because they use some sort of IR light that interferes with the sensor. That said, I would recommend paying someone to do it for you, I tried it myself and messed something up which broke mine. Canon once sold the EOS Ra, which has that removed by default, but they are hard to find and way too expensive for what you get.

@genmaicha However, looking at those, the prices on them have really started to inflate. Like, buying that one new today costs double what I paid for it about 5 years ago.

There are cheaper star trackers on the market now that are just as good, like the iOptron SkyGuider Pro (about $350), and iOptron SkyTracker Pro (about $230). However, I'm starting to think the best way for people to get into astrophotography is through smart scopes.

The Dwarflab mini and Seestar S30 are both all in one packages that can really get your foot in the door a lot easier. That said, it takes a lot of the technique out of taking images, and so a lot of people think of the as cheating, so idk.