I have 100$ Tritton PC510HDA headset, they are so bad compared to DT-770 and HD681Evo that I'm ashamed to confess that I had actually bought a pair... I doubt that other 5.1/7.1 headsets are any better.
I have the zalman ZM MIC1 for my 558's and it works well with voip, its a little quiet due to where you have to clip it. The Antlion modmic would be a better choice but for $8.99 I honestly don't have a problem with the zalman zm mic1.
If you want to get ripped off buy a razer headset.