Chile powder

Yeah, why not make your own?  You can mix them up, varying the chiles you use (there's hardly a wrong combination, it just depends on how you want to use them).  Just don't mix them up after the fact (i.e., you better keep track of your 8-habanero version so you don't get it mixed up with your mild version!).  Some chile powders are pure chiles; others (and most blends labeled "chile powder" than you buy at the store) also include things like cumin and paprika and garlic powder.  

Think about the things you cook and the flavors you prefer and do your thing.  Here's two examples, the first a pure chile blend from Daniel Boulud Braise cookbook, the second from Alton Brown is a more classic smoky Tex-Mex style (somewhere online).  The directions apply for both, it's only the ingredients that vary.  Either recipe makes somewhere between ¾ cup and 1 cup.

INGREDIENTS for Daniel Boulud's seven-chile powder

• 4 ancho chiles
  
• 4 pasilla chiles
  
• 4 guajillo chiles
  
• 2 chiles de arbol
  
• 2 pequin chiles
  
• 1 small dried habanero chile
  

INGREDIENTS for Alton Brown's smoky Tex-Mex chile powder

• 3 ancho chiles, stemmed, seeded and sliced
  
• 3 cascabel chiles, stemmed, seeded and sliced
  
• 3 dried arbol chiles, stemmed, seeded and sliced
  
• 2 tablespoons whole cumin seeds
  
• 2 tablespoons garlic powder
  
• 1 tablespoon dried oregano
  
• 1 teaspoon smoked paprika
  

DIRECTIONS

Place all of the chiles (and cumin, if using) into a medium nonstick saute pan or cast iron skillet over medium-high heat. Toast the chiles, moving the pan around constantly, approximately 4 to 5 minutes (if you're cumin, the smell of the cumin toasting is the sign it's done). Set aside and cool completely.

Once cool, place the chiles and cumin into the carafe of a spice mill or rotary coffee grinder (or, lacking these, a blender) along with the garlic powder, oregano, and paprika. Process until a fine powder is formed. This is important: allow the powder to settle for at least a minute before removing the lid of the carafe (if you don't, there is some bad and potentially painful chile dust floating in the air—now that could provoke sneezing!). 

Store in an airtight container for up to 6 months.