[apollophono]

Massdrop has the Sennheiser HD650 for $349.  That price is good
for only 6 more people.  If I didn't have the the HD600 already
and was looking for a great headphone buy this would be it.  I
have purchased one item from Massdrop and so far so good.  I
can't guarantee that for you, but you can do some research and
see if there are any issues using this site. 

[Noseyears]

There have been a good number of discussions about group buys on another forums (sometimes unauthorized distributors, meaning you are not covered by warranty..or fake headphones, refurb units and such)

I'ts not a bad idea to research before buying, thanks for the heads up on this deal.

[mdconnelly]

I've heard good things about Massdrop but have not (yet) actually purchased anything myself.   I've seen comments where shipping can take a long time.   It does seem like they like headphones and headphone amps.

[FullRangeMan]

I buy overseas since the 1970s and are surprised there is any seller prone to sell HD650s at this low value.
But as I have just buyed a HE400 with $100 off at the black friday from the factory site may be other bargains Iam unaware.