One quick way to assess the going rate for CDs is to go to a boot sale yourself and simply see what others are asking. Another is to trawl eBay through the "advanced search" facility, title by title until you feel you know enough. Remember that the selling price and postage together represent the eBay value, plus there can be significant fluctuations depending on demand. Beware though, certain artists and titles command more than others and multi-artist compilations are in a category of their own with some being sought after while others are scarcely worth the value of the plastic. Finally, you can check out second hand stores and be mindful that you would probably have to aim slightly below their prices. No doubt there are many ABers who might want to know what you are selling but there is no way to get together on this site.