Street Fighter X Tekken Xbox360 & PS3 is $20.60 delivered at The Game Collection
The Game Collection has Street Fighter X Tekken for $20.60 inclusive of delivery. They have the Xbob360 and PS3 edition of the game available at this price.
Did a quick check online and found the PS3 edition at $40.49 delivered at Oz Game Shop and $39 at Mighty Ape. The next best price I found was $24.98 excluding delivery at JB Hi Fi which has both the Xbox360 and PS3 editions at that price.