While I would most certainly agree that particular auction shows signs of - to borrow a phrase - "irrational exuberance"... it takes 2 to tango. It also brings up another point..
A recent GCA journal article on a RRAD rebuild mentioned that some collectors are doing a disservice to the M1's heritage by "correcting" what might be a historical rifle. The EP marking is part of the rifle's history, same as an MO or DDR mark on a Mosin, or some Waffenamt code on a Mauser. They are well-documented as to their origin, so are a historical point in the rifles path through time. In as-issued condition from the arsenal, it might fill some hole in someone's collection to that end.
For me, a "restored correct" rifle is really only worth the sum of it's parts, whereas an "original correct" would obviously be worth a good deal more. In the case of rifles similar to the linked auction I posted above - I would put a slight premium on an arsenal re-finished rifle (not THAT much) if it appeared unused, or showed all the correct hallmarks of that particular rebuild, or was otherwise documented to that effect over a run-of-the-mill mixmaster - or perhaps even a "restored correct" rifle. Condition and provenance is everything, though.
I'm NOT saying that is what the original poster has, and would agree the value for his is somewhere in the $900 - $1400 range (perhaps more - depends entirely on the venue and interested buyers). It doesn't look in the condition to warrant any sort of "irrational exuberance", at least the owner can point to something that shows a part of it's history. (Edit - it is a nice rifle in any case!)
IR