A quick question related to Amperex Bugle Boys

Yes you are correct. Almost impossible to fake the acid etched codes. After a great deal of experience, you become aware of the internal structure of certain types from certain manufacturers. Even the thickness and shape of the glass become familiar. One of my greatest irritations currently is the contention that Sylvania Bad Boy 6SN7s extend beyond the true bad boy which is a very distinct tube. 

Assuming that this can be considered a high price for a dual triode (stereo) preamp tube relative to its NOS availability, when might someone attempt to perfectly clone this Amperex tube?

There are fake Bugle Boys out there already.  Along with fake just about everything else.  They are not that common though.  As @audition__audio  said  if you have a lot of experience with tubes, more than I have, you can spot fakes by examining the structure.  They don't make them like they used to.