If you don't do slideouts, you can get a nice new rig in the $100-$125k range built on a good condition used cab/frame/drivetrain.
My opinion is that slideouts stink. They reduce overall reliability (weaker frame) and introduce their own multiple "points of failure".
Another point: some makers are getting away from the original riveted aluminum skin on welded steel square tube frame. They shouldn't. I have an '88 built that way, a very early truck conversion and it's aged VERY well. GMC buses going back to the 1940s and prior were riveted aluminum on aluminum frames and are still going strong; Crown schoolbuses were riveted aluminum on steel frames...the company has been out of business for what, over a decade, school districts still run models from the '70s and prior.
Rivets don't look "modern". They don't look "Prevostoid/Marathonish". They look "commercial", like a semi tractor.
They will also be firmly on there long after glued on "smooth sides" have gone to crap.
The absolute best deals on used truck conversions is on http://www.racingjunk.com
under "towing". Definately check that out.