I think we would all agree buying direct is better option then buying that Craigslist he mentioned. And that is before you take in fact it sounds he wants BTC 1/2 in advance for Craigslist ad.... which sounds scamy to me still.
Even at the higher B8 price I would still do that over his offer he had. It is true he could get lucky or not lucky on B9 shipment date no way to say for sure. So it is a gamble.
Its not much Gambling with craiglist however, its a garanteed "Throwing BTC down the drain." Regardless, the buy now price of S7 is still better than best case scenario with Craiglist so there is not much point in considering the craiglist offer. The PSU from Bitmain is arguably cheap. I would go with an alternative, however. Especially since it need 240v and there are better options here.
For 120v i'd go with Avalon6 no contest, since ATX PSU at that capacity range are still affordable.
I would not consider 240 a lesser option or PSU's that run on it. It is actually a really good option just not everyone is set up for it. But for those who can I would go 220/240 go for it. I really like it in my hobby mining area.
S7 could go on 120 to, its just for a ATX psu with 10 PCIe is so expensive. There are not many and they are a lot higher then a 240 server psu that is as good if not better on some.