There are certainly the odd purlers out there but I have seen comparitively few "really" good deep sky DSLR images. The final imaging results from a mono CCD with colour filters in the right hands, while more time consuming to capture and process, will out perform a DSLR in similar hands in colour fidelity, resolution and noise everytime.
The problem is your price range, unfortunately there aint much in there I am afraid, you would need to go small chip or cheap one shot, but one shot will have a bayer matrix again so while your noise is lower due to good cooling compared to a DSLR down goes your resolution again
In my opinion I would spend the money on getting the best mount you can that will provide the best tracking possible then continue with your 350D DSLR and take long exposures ie several hours and use good darks and flats and you should be in business
Mike