The important part here is the barrel condition. At the time those guns were made, all the ammuntion was corrosive primed and few of the owners (mostly boys with short attention spans) bothered to clean the gun after shooting it. The result is that even some guns in outwardly good condition are just rusted out or shot out inside. There is some collector interest, but there were so many made that unless the gun is in near new condition, it has little value. FWIW, I consider $200 is way too much for a Remington RB .22 in average condition.
(The Blue Book and other value guides are great and very helpful. But many dealers, on encountering something unusual, just go to the left hand column - like new condition - and price accordingly even if the gun itself is a piece of rusted junk.)