Cheapest Place to Buy Macbook Pro?

Getting $300 in vouchers from smsfun switch to optus promo, but dont know which vouchers to buy, dick smith, jb hifi or david jones. I want to buy a macbook pro at the end of the year, question is which place would be the cheapest to get it from? Which place is most likely to have sales on macs? there are occasionally 10% of apple products yeh?

thanks :D