The pix in the POTD thread are made with all kinds of cameras, from el cheapo point and shoots, to big-bucks full frame dSLR's. The best ones, IMO, were made using dSLR's, although not necessarily hugely expensive ones. Surprisingly, many very good ones are made with inexpensive digital cameras. In many cases, you can *right* click on the image, to access the EXIF information, which will give you the camera model and exposure information.
As Master Mason suggested, you might want to post some brief specifics about what kind of camera you are looking for, and your anticipated budget.
~YEKCIM