Coxon Belleek was one of the American companies that tried to take the Belleek style and try to make their own version of it in the US. Out of all the companies, it had probably the best quality. One reason is that they hired Irish workers (some even from Belleek). They were only in business for a few years in the late 20s. Most of their records and "true" names of the patterns have been lost. Out of about 100 patterns there's only a handful that collectors are sure of the actual names.
Based on my records, 12 cups/saucers should have a current market value in the range of $550 to $600.
Sometimes individual pieces will go higher if they're sold individually. Most people already have part of a set and might just be looking to replace a single piece or add to their collection. It's possible you might get a higher figure than the set replacement value by breaking it up and selling each cup/saucer on their own.
Prices will vary a bit depending on the condition of your pieces and where you try to it. Online markets (like Ebay) and garage sales do tend to go for less.
You will definitely get a higher value by selling it yourself than dealing with a shop or auction.
Craigslist is a worthy shot because it's free. Etsy
are turning about to be a great alternative to Ebay. http://www.bonanza.com
are pretty good up and coming online sites.
You might check out the consignment cost with any local antique shops. Some places charge about 25% to 30% of final sell price, but in dealing local you generally have less competition. It's always worth checking out.
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