ST11 YJF is a new style registration number and is our own stock number and therefore you will not find it cheaper or get it transferred quicker anywhere. The registration is currently on a vehicle so it will take 5 - 7 working days for the DVLA to process a vehicle-to-vehicle transfer.
This style of number is tied to the date in which it was initially released. Created as part of the '11' release, this was in March 2011 and so your vehicle must have been registered on or after this date. You can make a vehicle look older than it is by putting a registration on which was released before your vehicle was manufactured, but you cannot make a vehicle look newer than it is by putting on a later registration.