I belive thats the best offer for a larger ammount of Au for the seasoned player. I personlly never got that but I heard my clanmate was getting it quite often, like once a month some time ago but he spends a lot more on the game than me. There are better offers in gold but only for new accounts, something like 2.99 for 5k and 4.99 for 7,5k if I remember correctly. You get those around level 10 on a new account.
There was a really good one a few days ago too but cant remember exactly. It was $15 for 9,000 or something? I may be wrong the exacts but it was one of the best I have seen.This one is about the same if I am recalling correctly.