If you report her misrepresentation to the owners of the flea, you may get at least a measure of satisfaction...she might get her keester thrown out of the flea market. On the other hand, the flea people might just say...."We're only a venue, not responsible for blah, blah, blah...."
I think the owners can only be held accountable for sales of stolen merch. in their venues...But, you still should share the news of the dealer's sales tactics, in my opinion.