Q: I sold a work of art to a collector for $50,000 and found out later that I could have easily sold it for $75,000. Can I claim ona’ah and revoke the sale because of the unfair price?

A: Collector’s items, such as works of art, usually do not have a definable market. The regular rules of supply and demand do not apply here, but rather each person pays as he sees fit to evaluate the item. Therefore, such items are not included in the laws of ona’ah, because it is impossible to define a “fair market price” for them.

On the other hand, items that have catalogues with defined prices, such as stamps, would be included in ona’ah. The officially listed stamp value does not necessarily determine the actual “fair market value,” though, just as the “list price” of books does not necessarily reflect the actual “fair market value.” Nonetheless, the fact that the catalogue creates a definable market with a limited price range subjects stamps to the laws of ona’ah. Extremely rare stamps, however, would be similar to works of art and other collector items.