A mistake was just pointed out to me which I've now corrected and adjusted the price to $400 USD/BTC. This give the following results.
SP35 costs 4,035 USD inc. PSU + shipping for 6 Th/s at 3.5kW, it would take 147 days to break even,
10 x AM Prisma costs 7760 USD inc. PSUs + shipping for 14 Th/s at 10.5 kW, it would take 185 days to break even, and
S3+ B9 costs 232 USD inc. PSU + shipping for 453 Gh/s at 355W, it would take 176 days to break even.
Profit per Th per day:
SP20 = 3.25
SP35 = 3.4
S3+ = 2.92
AM Tube = 2.1
AM Prisma = 3
Where are you getting S3+ a psu for $232?