I don’t have much luck locally but when I do, it’s usually at thrift/antique shops and flea markets. There is an antique festival held near my town every year and I’ve found ponies there nearly every year.
My best find was Italian Polly (White with pink hair and hearts) for $2 at one of those festivals. She even had her original ribbon.
Another good find was the Dream Castle with most accessories, several ponies including a princess with her accessories, and four different porcelain ponies/scenes for around $80? I forget the exact amount but I was so excited in that moment! I already had most of it but finding pony items in person is so much more exciting than buying online.
Nicole