Front porch post

Hope someone can direct me as to where I can buy replacement post for front porch that need to be replaced due to wood rot. I have attached a picture of the top of the post as this is all one piece, I trying not to have to replace all 4 post by hoping someone knows or has replaced theirs. Lowes, Home Depot, tarp & lumber yard off Catoctin do not have these.

 

We had the same posts/finials and cut off the finial and replaced it with one from Home Depot or Lowe's. Bought a wood one, painted it and attached it (don't remember how though, screwed in?). We've since replaced all the railings/posts due to the wood posts rotting. But, it was a good fix for the problem.