For the moon and planets, you should consider a Webcam -- see for instance http://www.astronomyhints.com/webcam_make.html . If you don't want to hack your own, you can try one of the low-end imagers from the usual suspects, such as the Celestron NexImage Solar System Imager.
You should also consider afocal photography: http://www.aoas.org/article.php?story=2007062522295274 I use a universal mount with a point-and-shoot and it does very well with the moon.
If you want to hook directly up to the OTA using a T-Ring adapter, I'm not sure what the D50 does, but I can set up my Nikon D80 to behave well-enough. (Of course, my D80 still has an IR filter, which you'd want to get rid of in a dedicated astrophoto rig...)
Update: I totally forgot about "live focus," which Nikon's of the D80 and D50 generations didn't have. If I were to buy a DSLR with the intention of regularly using it for astrophotography, the ability to use the LCD to focus would be a MAJOR factor.