Water beds are still made and sold however the water beds are not as popular as they once were and are not seen for sale in many furniture stores in the USA.
To buy a water bed you usually have to have the furniture store specially order the water bed for you or go online and search for water beds and order the water bed online and have the water bed shipped to your door.
I used to see water beds being sold in furniture stores before years ago and my parents used to have a water bed but they are not as popular as they once were so furniture stores don't usually carry water beds for sale in their stores unless you want to order one.
Water beds are pretty comfortable but they can cause water damage so having a water bed in your house could raise your homeowners insurance rates as well and if the water bed were to get a hole in it or the water bed suddenly bursts and sends water all over your floor then the homeowners insurance may not cover the cost of the damage to your home.