I have a raised bar (counter top)that overlaps and is 5" above our island countertop. I am looking for 5" brushed stainless steel posts that will support the bar on the island counter top. The bar counter top is also supported on one end by a wall and the outside corner by a wooden post going to the floor (40 1/2 inches tall). We have been unable to find the stainless steel posts. Any source suggestions?

What diameter?
Look in Home Depot or Lowe's in the shower curtain rods or the towel holder section. These will be tubes not rods but may serve your purpose. If you can only find polished stainless, you can give it the brushed look with a wire wheel on a grinder.

Only other suggestion would be a machine shop or metal working shop.