Found used 2013 Rockwood roo 21ss. Right price?

That looks like a good price but would definitely not jump into it right away. It is late but there are still RV shows around and shop for the RV show price too. I have a Starcraft which is a similar floor plan to the 21ss Roo and the slide with the dinette and sofa works the best for me because it just opens things up. If you need that extra bed like the 21 dk, I would consider the air mattress Hide a bed option listed on Forest River's website.