[xur17]

You can rent hashing power on Nicehash, which currently has ~77MSol/s available for rent. I'm not 100% familiar with how the auction process works, but it looks like I could purchase 26MSol/s via a fixed contract for 1 hour for ~1BTC.

Am I misunderstanding something here, or can I maintain a 51% attack right now for ~$8k an hour. This can't be right.

[Uberphallus]

It is risky, but it is right, that's exactly why took a while to happen. A relatively small botnet can overtake many smaller coins in hash power in no time, that's the hypothesis where I'd put the money.

[mihaifm]

It should come lower than that...rental price seems to be around 0.5 BTC/MSol/day, so the price for one hour would be 0.5 * 26 / 24 = 0.54 BTC, roughly $4k