Do you have any existing 35mm lenses?
I don't know the latest prices, but I would look into Canon (5D), Nikon and Fuji (S3 Pro). See what resolution you need (higher if you want to print/publish your pictures) and how much you get for the money. After choosing your top contenters, read reviews (especially negative ones). Try them out if possible, see how you like the buttons and menus etc.