f.e.: http://www.cryptocurrencyminingreport.com/pb-mining-roi-oct-26th-weekly-payout-1-99-total-roi-92-61-23-weeks%EF%BC%81/
PB mining has roi after 31 weeks / 217 days and price is 0.0021 btc/gh
PBmining is the best priced offering by far but it's also a ponzi scheme.
Before they implemented a coinmixer it was easy to see the coins go directly from new customer payments to the "mining earnings" wallet.
There is no way that they can give you a 5 year contract on any hashing power right now with no maintenance fees. The power bill alone would sink them several times over. I believe "Ponzi scheme" is putting it mildly. Also, it is located in Canada but will not sell to Canadians. Go figure.
That just ranks of the mentality that someone scammed outside of canada will have little chance of retirbution, whereas if a canadian is wronged could easily take them to court