CHDK supports most of the main features on most cameras. The main exceptions are
- features that require hardware only available on certain cameras. The big one is that the ixus and most of the other cheap/compact cameras do not have an adjustable aperture.
- a few features require extra code, e.g. > 64 second exposures, DNG support.
What I would do is make a short list that are currently available, within your budget and size requirements, and then check the CHDK wiki pages for each camera, or ask here.
