Check online or your local yellow pages to find a qualified tack expert that can give you an idea what the mentioned saddles would go for.
Sears' main supplier appears to have been Capitol Saddlery, but the store also got saddles from the Wofford Saddle Company of Gainesville Georgia, and a few of the J.C Higgins brand made by the Bone Allen Company. There very well could have been other , but many of the saddles were not stamped with a makers name, just the Sears name and a model number.
horses
Yes
They aren't. Arabs have one less rib than other breeds of horses but that is unrelated to western saddles.
Boots and Saddles
In the horse world, you can have many types of saddles, but the two basic saddles are English and western. There is a cross between the two of them, but not as much people ride in them. The western saddle is much bigger and heavier than the English one, and has a horn. The cross is shaped as a western saddle, but does not have a horn.
There actually are. Depending on what discipline you use, or what kind of competition you are in, specialized saddles and multipurpose saddles are used all the time, in both English and Western disciplines
the ones that are tooled (decorated) are mostly for show. lots of leisure saddles have no tooling.
Blazing saddles? Blazing Saddles
saddles western styles
You could probably find used Western saddles at a farm, or pawn shop. Pawn shops' might be a little bit cheaper on the saddles, because farm ranchers usually take care of their stuff better.
Western rising saddles were developed from Spanish saddles brought to south America. The saddles found their way into Mexico where the cowboys there began changing them to suit their needs and eventually found it's way into North America.