I would suggest that you start with a small amount to see if you agree with your friend. I like cinnamon, and in fact used some today, but a little goes a long way.
I buy both stick cinnamon and ground cinnamon. The sticks are usually 3- to 4-inches long, typically about 15 to 20 in a jar. A stick of cinnamon is usually just tossed into the pot with the other ingredients, maybe sauteed (especially in Indian food), then discarded before the dish is served (like bay leaves).
The powdered stuff is added in small amounts, usually a teaspoon or less in savory dishes and maybe a couple of teaspoons in sweets, depending on the recipe. I buy it in small jars because as with most herbs and spices, it doesn't last forever.
If you do want to buy it in bulk, check any Indian supermarkets that may be near you, or go to one of the many on-line spice purveyors.