A good set of hanging scales can be hard to find. Some of the best brands are Chatillon and Detecto, but there are others. However Hanson seems to make no hanging scales that are legal for trade, so although they are less money, they are not able to legally be used at market.
Although any scale may be used to weigh the contents of items brought to market, scales used at the point of sale must be labeled legal for trade. This means that the scale uses springs that compensate for temperature differences, and thus will weigh accurately within a wide range of ambient temperatures. An agent from the Maine Dept. of Ag's Division of Weights and Measures is likely to visit your market to assure that everyone's scales are accurate for a manditory fee (usually $5-15 per scale).
Examples of websites where scales can be purchased online are www.scalesgalore.com in Brooklyn, NY
which carries a wide range of scales of all brands and types; and Ohio-based www.chatillon.com which is the actual manufacturer of the most popular hanging scales for farmers' markets. From either site, the model 0723TG, rated "legal for trade", runs about $300 with galvanized pan. Shipping is about $8.00. It has temperature-compensated springs, which means your mess of beet greens will weigh as much in June as in October.
Another useful company is ULine.com which has several scales available as well as traffic cones and packaging materials such as mesh onion bags, and a wide selection of plastic bags. Their free catalog is ¾ inch thick.
In 2010 we discovered Drillspot.com where we found the best price for a Chatillon hanging scale.
Each of these sites also has portable digital scales, and more other types of scales than you probably knew existed. You can enter "scales" and your favorite brand name into any search engine to find more websites offering scales online.