XIV Karats will be a little more compared to downtown due to their location and their name, but they have a nice selection and a broad price range. I like that they have more unique pieces, over the commercialized pieces in most of the downtown booths. XIV Karats has really good service and that is another reason their prices are higher. They have a jeweler on site and can do most sizing so that you can leave with your purchases. XIV Karat also has period pieces, but I have never looked. They also have good costume jewelry that can pass as real.
I was there a few years ago (before I moved) and bought a couple rose gold diamond stack bracelets. About .20 tcw for $239. I don't even think I tried to bargain, young a stupid on my part.