IF you shoot low light events such as concerts go get a low light lens - preferably a 70-200 2.8 (it's useful for other stuff too)
But don't just go away and buy 3000k worth of equipment... Learn to take a good photo with what you have. There are so many amazing "semi-pro" or even pro photographers who started with very basic DSLR setup and took with that setup such amazing shots you would never believe!
:raisedbrow:
Did you even read the first post? OP is deciding between a speed light and a 50mm and you're telling him to go buy a $2,500 lens, but not to just go buy $3,000 worth of equipment.