If you compare it with the SL, TM, MP etc. the price is way too high for this helmet because it doesnt have the details like these lids. I dont say its worth nothing but its no way that good than the known authentic casts.
Well to be fair I've not seen this auction helmet in its unfinished state, although that would be nice to see. But based on the way the dome was treated, I doubt there is much in the way of fine detail left over on the mask. But still as far as being a really early pull it has some value. It is harder I think to put a value on a replica than on an original. The MP is a promotional helmet, the TM is reportedly from the ESB production, and the SL is "just" a pull from the Baker/ILM mold so each casting will have different things to lend to its value.