Milk cans, planters, or big PVC or concrete culverts blocked at one end work as well. If you can find a sewer job going on in your town, there will be a lot of scrap pieces of big PVC in their waste pile from 2 to 5 feet long....got some of mine that way, just for the asking.

I cannot imagine them selling much of the above except to people who might have plenty of cash and are gullible.