Butterfly has the
600 GH/s Monarch for $2196. I think that is the cheapest per GH price I have seen.
http://www.butterflylabs.com/monarch/Thats $3.66 /GH
This one is $6.50/GH almost double!
The only problem is when I saw it first just 4 weeks ago, the BFL Monarch could make one BTC in 5 days. Still has not even shipped yet.
Now it makes one BTC in almost 9 days, ONLY IF YOU HAD IT TODAY, but you dont, BFL is using them to mine.
By the time it ships it will make one BTC in 50 days and that 50 days will never come because it keeps increasing while you wait for the 50 days. So its a never ending cycle.
Plus the moment the 45000 BFL cards get released and hit the market, BTC difficulty will quadrouple in a matter of few days so those cards the moment you open the box are obsolete.
Thats why the 6500$ price is justified if they can sent on feb 19 ...