Transitional planes were once, and to some extent still are, nearly worthless on the collector market.
In the early 1970's, when tool collecting began to take off in earnest, the collectors where most of the tools come from (within a few hundred miles of Mass), found themselves up to their necks in tools for nearly free. They collectively decided transitionals were inferior to the iron tools they were picking up by the wheelbarrow load whenever they wanted.
Since the parts of transitionals wouldn't easily fit the iron tools (that were so common to them they could barely resell for any price at the time), the trannys were piled and burned for sport during tool get to-gethers.
To some extent the prejudice still exists.
Transitionals were cheaper when made. Beechwood instead of rosewood handles and no iron body to cast, season and then machine etc. meant Stanley could sell them for less.
They are also less brainlessly usable. You have to work on them some when you get one, and use your noggin as you do.
Trannys have a moveable frog to set the blade opening in the body, just like iron planes. But you can't just slide the frog forward to close up the mouth. If you do you'll have 1/2 the blade suspended in mid air and it will chatter to beat the band! You have to shim the wooden bed to compensate. Thin wood or heavy veneer in the proper thickness works a treat though, and Stanley suggested to use ordinary cardboard!
The handles need attention to keep from squirming in heavy use. The mounting hardware was a looser fit. For myself I will mix up epoxy putty and generously coat the hardware and frame with grease. Then pack the handle and screw it on. When the epoxy cures it will only adhere to the wood and make an exact interior mold of the hardware, which it won't stick to and can still be removed.
Squirm no more!!
Its always good to remember that the immortal Studley packed his own "most desirable toolchest ever made" with transitionals. His were custom cast brass frames instead of iron but still...........
Here is my own recreation of a Stanley #29. This is the size of a #2 iron plane. It has a rosewood body (SE Asian rosewood) and a very thick tapered blade. The throat is tight.
Considerable work was done on the chipbreaker to eliminate backlash in the adjuster.
yours Scott