The Tandoori mix is available at Mustaffa...not many Indian shops carry Ahmed brand. Another mix I strongly recommend is the Ahmed Briyani Mix...I think the packaging is slightly different at Mustaffa, the one that I have is bought at my neighbourhood Indian shop.
As for the other 3 spices, you can get at Malay shops, mostly at Geylang market - the fresh chicken stalls. They are stored with the other frozen food. I strongly recommend this as all of the mixes are authentic.