They are kinda' hard to find.. I want one that'll open up into maybe not a double bed,but bigger than a single bed, also not too expensive!
You can get a couch that opens up to a bed at most furniture stores. You can also try your local GoodWill or a thrift store.
Some furniture stores are:
My boyfriend actually got one off of Kijiji. I do believe I have seen that sort of a sofa bed at IKEA before, though I have not been for a long time. Won't hurt to check it out though!
you can either try amazon or ebay ? or a garage sale near to your place (:
maybe this would help http://www.ebay.co.uk/sch/Sofa-Beds-/101422/i.html ?
Try your local Goodwill or thrift store