I would highly recommend you make your own. If you buy the whole spices I recommend in my garam masala recipe you can use those for other spice mixes on this site. Whole spices keep well for a year or more. Ground spices lose their intensity after about 6 months, so if you buy whole ones, you can make different mixes and have them taste fresh. If you prefer not to make it, I would recommend either The Spice House garam masala, Penzey's garam masala, or small batches from places like Trader Joe, Sprouts, Central Market, etc. You can also try this Rani Garam Masala. Do NOT use Private Collection, which is nothing but Paprika, and very red Indian Grocery stores carry brands such as Shaan, Badshah, and MTR that work well.