Reddit reviews Innomax 600 SL 22 mil Semi-Motionless Waterbed Mattress King Size with Elegant Stand up Liner, High Volt Heater, Conditioner, Fill and Drain Kit and Soft Quilted Cushion Pad

Looks like yes.

They can be. It depends on what you consider expensive to be when compared to some potentially crazy expensive spring or foam mattresses. A basic bed is around $300. A "fine furniture" waterbed can be $1000 to $2000+, but so can a dresser or table.

You typically buy the waterbed frame as one purchasing decision, then select a waterbed mattress to go into it. A waterbed mattress must have a purpose made waterbed frame to hold it. You cannot put a waterbed mattress on a standard bed frame. You can also buy a cheaper waterbed kit that comes with everything.

A typical lower cost waterbed kit would look like this. I would highly recommend getting a full-motionless mattress, which has layers of foam inside of the mattress to dampen any waves and get rid of the sloshing feeling when you roll around or sit up.

You then need to decide if you want to sleep on the mattress directly, or get a pillow top cover for it. I like a "marshmallow" soft bed, so I use a thick pillow top cover over the mattress. If you don't have a thick comforter of some kind between you and the mattress, then the mattress will need to be heated. Sleeping on a cold waterbed mattress is really bad for you. A heater usually comes with a waterbed kit.

A waterbed is a hassle to setup. They are heavy and clunky and take time to get settled, but they are pretty much maintenance free after that. I absolutely love them. Do some research and watch some videos and reviews before buying.