In our experience, sleeper cabs on used trucks don't command a premium price. In fact one good alternative is the FL reconditioned day cabs. These are old FL Centuries that the factory takes, cuts off the sleepers and reconditions for re-sale. A moot point for you however. The Volvo engines get rave reviews re: fuel efficiency and that may be one reason to go to a new Volvo. Western Star is a great choice especially mated to a long box. It will have the look of a truck that can pull a big coach (even thought weight and size is never an issue for any big block engine). Good luck and contact us if we can help.
Tony
www.toolsetmotorhomes.com