I should dig out my Remington notes before answering this, but from what I can remember the Model 50 is just a feature variant of the Model 12, one that had a segment shift instead of the standard carriage shift. Someone more up on Remingtons than me will undoubtedly correct this if I'm wrong.

With respect to the serial number, I'm assuming you replaced actual digits with the 'xxx'? When it comes to typewriters, it's okay to post full numbers. If it is a number in the 60,000 range then it was manufactured in 1926. (I moved your post to the Standards sub-forum as this machine is not an Early typewriter).

What's it worth? Your location in the world would factor into it, but it really depends on the kind of buyer who happens to want your typewriter. For example, I rarely spend more than $50 for ANY typewriter model, but for every patient and pragmatic buyer there are dozens who seem happy to pay almost any amount for a typewriter; in other words, you could get anything between $10 - $500 CAD for it.