Looking for postcards to buy

I want to buy vintage 1900 - 1960 postcards that are unusual and in good condition.  They can either be mailed or not mailed.  Prefer USA postcards of street scenes, classic cars, route 66, motels and restaurants.  I will buy 1 postcard to a large collection.  Price must be right as I will be reselling them.  I will pay a good price for a rare postcard.  I will also consider Holiday postcards of Santa Claus, Halloween and others if extra nice.  I will consider any postcard.