The s9 seems over priced. To put this into perspective, let us compare S7 with S9. let say the aim is 14TH
1 S9 = $2100
1 Power Supply (from Bitmain) = $140
Shipping to the US (Fedex) = $75
Total = $2315
To get the same hash rate with S7, we need 3 S7s, 4.73 x 3 = 14.2TH
3 S7s = $1320 ($420 each)
3 power supplies = $420 ($140 each)
Shipping to the US = $140
Total = $1880
The difference is $435. If you think the space and efficiency worth the difference, go ahead and buy it. If not, (let say, you have a very cheap electricity, and plenty of space), S7 is a better option. If you ask me, I would say don't buy any of them. just wait until halving, the price will be more reasonable, and you can evaluate your investment better!
I think they understand the pricing pretty well here. The price of electricity has been established around $60/month. Considering 2 less minor this bring the price to 3~4 months. Everything is set for a ROI of around 3~4 months from now. But one thing is for certain, once these things get out into the public we can expect to see difficultly to start increasing by 20% again.
I was really hoping with halving people were going to start turning their miners off and difficulty would stabilize, but it looks like technology will continue to push difficulty up even after halving.