For any and all brewing spices, I recommend you check out the two big spice merchants: Penzeys and "The Spice House" (www.penzeys.com
). You will find very high-quality spices at extremely reasonable prices.
If you're in the Chicago/Milwaukee area, you can stop by one of the spice house's stores. Penzys has some here and there as well. Personally, I prefer The Spice House, because they'll sell you bulk spices without any jars/etc, which is great for refilling jars or if you plan to use it quickly (e.g. for a brewing recipe).
I also recommend them for cooking, needless to say. Cheaper than the grocery store, and higher quality. Can't be beat.