What is and what is not a good deal is a relative thing.
I'd probably want the $350 also if it was mine. However, those housing are date coded. I can't find any mention of a date code on this one nor a picture of the code.
Also, when installed, the radiator hose conceals a good portion of the engineering number so to me those two details diminish the value.
EXCEPT for the casting date, I was able to create out of the current Scott Drake offering, a housing that when installed looks correct.
So really to me, that auction resembled a bunch of decadent 12 year olds trading baseball cards saying, "got it, got it, need it". Not much else.