drive shaft

[MacRob]

Hi guys and girls
How do you know if a drive shaft has blown or more to the point the velocity joint has gone?
I ask as when driving and turning over 40mph there is no noise/vibration but when under 40 mph and turning or slowing down there is a kind of clunking noise. There is no play in the bearings that I can detect and the handling/braking is fine.
It seems to be coming from the driver’s side but as we all know sounds heard from inside the car can be coming from either side.
Are they straight forward to change or would it be better to change the whole drive shaft? Need the cheapest option as money tight.