I would think higher. A reg Powerhouse 410 is $850. new, the Road ready would be more. Used, I'd think maybe 25% less, but that's still more than 500 bucks.
Nope. Resale on the Road Roady cabs unless MINT is usually pretty low. You can pickup a Powerhouse in the 500-700 range used in decent shape.
If you mean older non-Diesel/Powerhouse stuff, $350-$500 is what I've seen. Great cabs but heavy(I have a RR 1X15).