Mark,
I do here your pain & your points lend themselves to an approach that only works with thieves with common sense. (to a certain degree)
You do have idiot thieves who make high-end forgeries of low end items - but wait a minute, maybe that makes them smart thieves...
Unfortunately Mark, your comment only works in the scenario you played out - that is not reality though... Very convincing forgeries Have been made for low or medium priced items and proved to be quite profitable.
Your comments still do not change the fact though that until materials testing is done on any photo, one cannot prove that it is not a fake regardless of the value.
Also, thousands of Expensive photos have been sold at BIG auctions over the years... I have never seen a chemical analysis in any of the auction catalogues nor do I recall us "Net54" ever crying out for one to be done?