Vibrating front wheel when braking

[wisefi]

Hi everyone. I recently bought a 2010, 1.25 ZETEC. It has a problem perhaps someone can shine a light what the problem can be:

Whilst cruising over 50 km/h (actually it does it at lower speed too, but it's more visible at higher speeds) when I press the brakes, the front right wheel starts to vibrate (wobble?). I do not feel any shake on the steering nor pulling to a direction though, nor no vibration whilst driving.

What can it be ? I am short on cash at the moment, that's why I am trying to find out what the problem is before replacing the parts.