Hi David, thanks for picking this up. I am primarily a Lemania collector too and of course the AMI-issued, L5100-based Heuer reference, which sadly I have never known, is both a Lemania and Heuer grail.
And indeed the one you've brought up is neither: obviously not a Lemania, not a Heuer - and I am very doubtful that it was ever issued by AMI either or even submitted as a prototype - pls. note my extreme political correctness here ;-).
This looks like quite a common V7750 somehow doctored with the 3H logo, a quite questionably shaped Heuer shield and AMI acronym.
I do not follow auction houses and I suspect many here who do may have chosen not to care too much for this particular one.
On all accounts, I fully agree with you: to me, this looks like a franken, worth much less than it was paid for (heaven forbid a buyer's premium was atop of the sum!). On the other hand, we shall never know how some sale go - otherwise would we see all those "sold" items pop up again after a few days, mostly on the same sites?
Caveat emptor, really - and buy the seller first.
Cheers,
Fabrizio