Did you intend to post a picture or link?

Cedar lasts a long time. Galvanized or enameled metal ones are pretty popular. I've seen a few heavy plastic ones too. Some folks do it DYI and pop a kiddie pool on a table or put an old bathtub on sawhorses. Stacked strawbales on wood pallets can make a decent elevated bed too.

Need a picture.

Are you trying to describe basically a container with legs? If so I would always use a liner, plastic or metal, within any wooden frame. The wooden bottom will rot faster than say the sides of a “ raised bed” which has no bottom. If it’s a true container planter there’s no benefit to a wooden bottom. Whereas I’ve used cedar for raised beds just because I like the look, even though they won’t last nearly as long as metal or plastic or composite.