If you want to mine Bitcoin without going through hardware setups and managing your miners all the time then check out my signature.
Cloud mining is a very reliable and easy solution for those who want to mine Bitcoin and don't want to spend time supervising their miners.
I myself am very busy and have found it very helpful.
cex.io is very reliable? You must be kidding me lol.
Anyway, the price there is highly overpriced, and you can compare the mining revenue with the hashrate price easily here. http://cex.io/calc