Totally agree, 40/56Gbps can be had very cheap now (and silent!)
My experience with this is IS5022 (QDR, ~$80) or MSX6005 (FDR, ~$100), a bunch of ConnectX-3's (around $30 for HP branded) and a cables (10m fiber can be found for less than $15).
The best feature about IS5022 is on the attached...