You can't compare the price of ghs per ghs of Antminer S1 180 ghs machine to the price you pay to buy a single ghs unit. You got it all wrong. If you want to compare 1 ghs to antminer you have to compare it to the Antminer U1 1.6 ghs USB stick, not to a 180 ghs machine. CEX is not for people that want to buy 200 ghs, unless you are great at trading, it's for people that want to buy a few from them without the hassle of equipment, software, reselling a physical product that its almost worthless in 3 months retarded greedbags who can't do math and don't mind losing BTC in an epic scam, etc. etc. It is also for people to point their miners at ghash..
and if you are smart, you can actually mine for free at cex...the price has not moved much in 3 weeks...that is 3 weeks of free mining as in Zero cost.