I am looking to replace a very cheap (and hard as a rock) mattress in our guest room. I want to get something of reasonable quality without breaking my bank account. Any feedback on a particular brand you might recommend or a location where I might find the best value would be appreciated. Also, is it okay to keep the existing boxspring and just purchase the mattress itself? The bed is a standard double size. Come on sleep experts! ------------------ The Dark Tower Fearless Vampire Killers (1967)?