There are two pins available which have slight variations in colour. These are pin 1 - the pink logo and pin 7 - 4 Years to Go. Each pin is described as pink when in fact there is also a purple version of the pin. This variation came about as part of the manufacturing process. The manufacturer originally made the pin and produced the colour as shown on the right in the picture below. This pin was distributed and shortly after this, it was decided (I imagine by LOCOG) that the colour was not correct and that a new pin should be issued with the colour adjusted. This is the pin on the left.
The pink logo pin is not from a limited edition however the 4 Years To Go pin is. The question therefore is - Does the limit number apply to each pin and how many pins are there - i.e. are there 5,000 of each or 5,00 between them?. The answer is - we don't know. The purple variety was definitely withdrawn from sale when the colour was changed, however there's no record of how many were sold. The pin was only available from 2 outlets, so I think numbers will be small. The second version of the pin was produced in a batch of 5,000 and these are the ones available at the moment - if you can find one. Both pins come on the version 1 blue backing card and from personal experience, the first (purple) version has a limited edition sequence number printed on the card whereas the second (pink) version does not.