Since I have both bought and sold on the Marketplace Forum over many years, I’ve found specific threads about specific products to be most effective. Using your example, I suggest separating your auction posts by system. Rather than a “Lots of rare stuff” title, provide separate posts for Vectrex, Colecovision, etc., each with its own specific title. That way you are targeting equally specific audiences, and those potential buyers who may be looking for ONE needn’t bother looking through ALL to find their items of interest.