I was surprised by the number of potential sources that I found, but that is partially due to the number of automotive suppliers of this type of thing in the area.
One potential source can be found at www.style-mark.com. I knew of another in Metamora, MI and they might be the source that is gone. But in searching for them, I went to www.switchboard.com and put Polyurethane Products-Manufacturers in the business category section. You might try this for your area and see what you find. Don't forget to put the checkmark for "close to" and not one city or town name only to be searched.
I do know that I would much rather use real wood for this, particularly from a fire safety standpoint.