I have several plates and am looking for others who collect

Ebay has category-specific groups, but I think the closest is China.

Are you talking about dinner china or collector type plates by companies like Hamilton or Bradford exchange?
Those companies guarantee the value to increase over the years, but I have yet to see many that go for more than $30.

Are you looking for a price for your plates, or are you looking to join a group that also collects and wishes to discuss these items? Based on your post, it didn't sound like you were looking for an estimated value of your merchandise, but more of a group that's interested in the same merchandise.

More info would be helpful.