We bought a 2004 Newmar 4011 10yrs old with 30K miles from the original owner. I would never buy a MH from a dealer. It has been a wonderful coach that we pamper and store inside when not on the road just as the original owner did.
I am a big fan of the Spartan chassis with the Cummins (ISL) diesel. I do my own maintenance so I am especially fond of the side mounted radiator. I have owned 2 ea 8.1 liter gassers and there is no comparison with the power and torque of the diesel.
I have never owned a Tiffin or American Coach, but I'm sure they are good equipment. I have a friend with a Tiffin and it is really nice. I'm just not a fan of his rear mounted radiator.
I would suggest that you settle on a brand/floor plan/equipment/model you want and place want ads in your local paper, Craig's list, this forum, etc with your desire to buy. You will be surprised what shows up.
Rick and Lynda Smith
2004 NEWMAR DSDP M-4011-SPTN 8.9 Liter Cummins
2011 GMC SLT 1500 4WD CREW toad