You'd be hard pressed to do better than the 20d for sale as JJJ said:
http://www.iceinspace.com.au/forum/s...ad.php?t=79810
Many people think Canon has never produced finer cameras for AP since this era. Liveview is very helpful if you can get it, and you won't get HD video until later cameras (shouldn't be an issue though from what you've described as your need).
Big bonus for AP to buy a modded camera, although for daytime use you'll have to do white balance adjustments (worth reading up on). The beauty of buing a good 2nd hand camera here is you shouldn't lose out much on resale in the future if you continue to look after it.
Weight and mounting options are worth considering too. I'm happy with my 450D as it's significantly light on my scope than the stronger but heavier XX series cameras (let alone the top line X cameras). Have you had an SLR on the scope yet?