Are you looking to flip the machine? I've never seen a transverse shuttle in person, only pictures. Try looking up Frister & Rossman Transverse Shuttle sewing machine
This machine looks just like a picture of the F&R I saw.
Generally, a machine is worth what someone is willing to pay, most often they are not worth nearly what people think they are worth (right now on craigslist in my area there is a 15-91 Centennial for $900). Value can also depend on availability of parts and accessories or if the machine has the necessary parts to run. E.g. does this machine have a shuttle? What bobbins does is it take? What needles? Etc.