An alternative live mic for singers worth mention is the TC Helicon MP-70..


http://www.tc-helicon.com/en/products/mp-70/

"Best-in-class off-axis noise rejection and feedback suppression"

Online reviews are positive.

Introduced to rival the sure sm58 at a similar price point.
but if you shop around they have been sold as low as £25
in shop promotions & lightning sales.

[I grabbed a couple at that price primarily to use with a vocoder]

It may possibly just have been discontinued.

There is the higher priced MP75 which has a switch enabled for use with specific TC Helicon vocal processors.