Super wrote
...are we sure those tracks are authentic and not 3D printed?
Both 4-packs are available from TakaraTomy Mall, 660 yen each. Plaza Japan would not be selling anything other than these genuine ones, but I agree that general availability does seem to be curiously restricted. Maybe most vendors don't think they'd sell many at a price of well over US$1 per piece? A 4-pack of regular straight BPT costs 440 yen from the same source.
I don't see that manufacturing cost would be any different, except that short runs always cost more, so this mark-up is likely due to an attempt to pass it off as a 'premium' product in line with the whole Real Class strategy.
