White was quite rare in the MK5's but is very common in the MK6. Suprised its hard to find one, but guess its the spec your after narrowing it down.
I originally wanted a white one, but found a fully loaded Tornado Red, which is probably my favourite colour for a GTI, ticked all the right boxes, at a great price, so went for it! Havent looked back, stunning colour!
But if its white your set on, wait for it or you will be dissapointed.