Hi Andy
I'm a bit late jumping in, but here's my pennyworth. We're on our fifth RV in the States (currently a 2008 Newmay Kountry Star). When negotiating, the advice we were given was start by looking for a one third discount, and do not settle for less than 28% - and that worked with all of them. Once the salesman is hooked casually mention a few extras - they often have more leeway with those than with straight cash. If you're buying in Florida, Lazy Days come to mind, being the biggest on that coast. Not our choice (we prefer the West Coast) but we did buy a 5th wheel for a Brit friend from them, got a very good deal on price, then asked them to transport it to Jacksonville for the ferry to Southampton, which they did free of charge. Then when he had problems with the awning in North Wales, they shipped a new one to him without any hassle at all.
Best advice I've read in all the postings, is to come on over, look around all the RV dealers, enjoy the experience and have fun - a week in a motel (if you can't get the time share you mejntioned), a week's car rental, ?400 each for the return flight, ?1250 for the lot and you'll have a ball - and save a ton of money too.
Terry (enjoying the sun in Arizona)