A go - is.............. let me think of how to say this. Ok, you're at a bowling alley, you are with 5 friends, they all throw the ball but they do it one person at a time, they all have "a go" their go. "Let me try, it's my go". To charge for something $1.99 a go, means $1.99 for every time you buy it. I'm stunned at some of the poor answers in here sometimes.

Here it means $1.99 for 'each' song download. It is a British term but Canadians and Americans do use it as well but not as much in this context, usually they say it to mean each 'turn'. For example: 'The rides at Disneyland were at least $15 a go'. The primary meaning in the US and Canada is that it is ok to proceed with something or that something is going to proceed/happen.

That it is going to happen