I try to compare prices and the ingredients in the spice blend to determine which is the cheapest option. I also sometimes compare the flavors by making a batch of something with my own spices and another with a store bought blend. A last consideration I make is with regard to health issues. Some spice blends have a really high salt content, and salt intake can make your blood pressure go up. Obviously with pickles some salt is needed, but comparing the salt content in your recipe and the salt content in the prepared spice blend may also be something you want to take into consideration.
I got my Penzey order today. They tossed in a free sample of their BBQ300 or whatever. SALTY!!!!!!!!!!!!!!!!!!
I will have to dilute it down a ton to be able to use it. Plus there is something else in there that I am not a fan of. Its either too much ginger, nutmeg or allspice. Not sure which one, but hopefully the dilution takes care of that.