Hi Robin,
I’m not sure if you’re looking for an adjustable bed and a mattress or just an adjustable bed but either way I would buy them separately unless you find a mattress that is perfect and they also happen to sell the adjustable bed that you want as well at a better price than it would be available elsewhere (perhaps because you are buying both).
The adjustable bed thread here should be helpful and has some good “value” sources as well.
If you are also looking for a mattress then the tutorial post here is the best place to start.
If you used the search window at the top of the page then that search engine doesn’t search the forum … only the pages in the main site. The “search forum” tab just under the main menu is where you can search the forum posts.
Phoenix