why is there such a price difference for different gold bracelets?

There are several factors that directly bear on, and influence, the price of fine gold jewelry.  This would include bracelets, but also rings, necklaces, pendants, and so on.

First and foremost are jewelry items made by top designers such as Cartier, Tiffany, Roberto Coin, Bvlgari, and others.  Here you are paying not only for the gold content, design and manufacturing quality, but the aesthetic of owning the designer name.  Take three gold bracelets with a similar design, one by a fine Italian goldsmith, the second by Tiffany, and the third by Cartier and you'd likely see prices of $1,000 for the Italian goldsmith, $6,000 for Tiffany, and $10,000 for Cartier.  
When speaking of fine gold jewelry NOT made by the top designers, cost criteria includes manufacturer, unique design or form, and eye appeal; fineness of detail; finish and construction; and weight and gold purity (i.e., 10k, 14k, 18k).  For example, we find that Italian made gold jewelry is, in the main, better made and of better quality than gold jewelry from Turkey.  Too, finer jewelry tends to be of heavier weight.  Given two similar bracelets in 14k gold, one with a weight of 12 grams and the other weighing 9 grams, by rule of thumb the heavier bracelet is probably the better made of the two - but still bears examination.
We expect that our clients are purchasing jewelry items that will ultimately become family heirlooms so we are very selective of the jewelry we acquire.  We examine each piece for design appeal, karat purity, origin, weight, condition and fineness of detail so that each piece can become a quality heirloom to pass on, and then pass yet again, and yet then again.